Cramming doesn’t work. Not really. Sure you might pass tomorrow’s exam or compliance assessment. But ask yourself the same questions a month later and most of the answers will be gone.
There’s a better way. Spaced repetition works with your brain’s natural forgetting curve instead of against it. Review information at the right intervals, and instead of fading, it sticks.
It’s why apps like Duolingo, Memrise, and Anki are built around the principle. And it’s why organisations should be paying attention. According to Training Magazine, US companies spent $102.8 billion on training in 2025. That’s a lot of money to lose to knowledge decay.
This article covers how spaced repetition works, what the research says, and how to use it. So, let’s start at the start. And come back to it later. That’s kind of the point.
What is Spaced Repetition?
Spaced repetition is a learning technique that reviews information at progressively increasing intervals. The trick is timing those reviews to catch information just before your brain forgets it.
Think of memory like the battery on a phone. Without recharging it, it drains away. And the longer you wait, the more you lose. But if you plug in just before it dies, you preserve what’s left and top it up.
Each review of a piece of information works in the same way. Review it before you forget and you reset the decay. Wait too long and you have to relearn it. Remember, the intervals should expand each time. A day, then a week, then a month. The more familiar the information becomes, the longer your brain can hold onto it.
The opposite is cramming or blocked practice. Cramming stuffs everything into one intensive session. It can get you through tomorrow’s exam or assessment, but a month later most of it will be gone. On the other hand, spaced repetition offers desirable difficulty. It may take longer to see any progress, but the gains last.
The Forgetting Curve: Why We Forget What We Learn
Our memory is fallible. Without active review, information starts slipping away from us within hours. By the next day, much of what we learn is already gone. This pattern is called the forgetting curve.
German psychologist Hermann Ebbinghaus first documented it in the 1880s by testing his own recall of nonsense syllables over time. He was able to show that memory decay follows a predictable shape. Murre and Dros (2015) successfully replicated Ebbinghaus’s findings in modern conditions, confirming the curve still holds today.
Spaced repetition exists to counter that curve. By placing reviews right before we’d otherwise forget, we move information from short-term to long-term memory. Each review flattens the slope a little more. The result is a steady upward staircase instead of a steep downward slide.
For the full science (and a deeper look at how to combat the curve), see our guide to the forgetting curve.
How Does Spaced Repetition Work?
Spaced repetition relies on active recall, not passive re-reading. To reset the forgetting curve, you need to actively pull information out of your memory, not just look at it again. That’s why most spaced repetition systems use flashcards or quizzes. They force the brain into retrieval mode.
Flashcards are the most common tool. The principle is simple: cards you find easy show up less often, while cards you struggle with come back more frequently. This focuses your attention on what you don’t yet know without wasting time on what you do.
The classic example is the Leitner System (sometimes called the Box Method). You sort flashcards into a series of boxes. Cards you recall correctly move to a box with longer intervals between reviews. Cards you get wrong drop back into a more frequently reviewed box. Over time, well-learned material drifts to the back, and difficult material stays close at hand.
Modern spaced repetition apps automate this logic. Algorithms like SuperMemo’s SM-2 (used in Anki for years) and the newer FSRS, which Anki adopted in 2023, calculate the optimal interval for each card based on your past performance. The result is a personalised review schedule that adapts as you learn.
As author Gabriel Wyner put it in Fluent Forever: “Playing with timing in this way is known as spaced repetition, and it’s extraordinarily efficient. In a four-month period, practicing for 30 minutes a day, you can expect to learn and retain 3600 flash cards with 90 to 95 percent accuracy.”
Spaced Repetition Intervals: How Often Should You Review?
How long should you wait between reviews? Unfortunately, there’s no one-size-fits-all answer, but the research gives us a useful framework.
Cepeda et al. (2008) studied over 1,350 learners across retention windows of up to a year. They found that the optimal review interval declines as a proportion of how long you want to remember. The further out you need to remember, the closer (in proportional terms) your reviews should be.
- For 1-week retention → review at ~20-40% of the gap = 1-2 days
- For 1-month retention → ~10-20% = 3-6 days
- For 1-year retention → ~5-10% = 18-37 days
Common Spaced Repetition Intervals
Over the years, several practical schedules have emerged. The most common are:
| Schedule | Intervals from initial learning | Best for |
|---|---|---|
| 1-3-7-14-30 day method | Days 1, 3, 7, 14, 30 | Short-to-medium term recall, exam prep |
| Expanding schedule (based on SuperMemo’s SM-2) | Days 1, 6, 14, 30, 66, 150, 360 | Long-term retention |
| Pimsleur’s graduated interval recall | Seconds → minutes → hours → days → months | Audio language learning |
| Adaptive algorithms (Anki’s FSRS, Duolingo, etc.) | Personalised per learner | Most digital learning in 2026 |
These are starting points, not prescriptions. The key is to find an approach that works for you. We recommend starting with shorter intervals and gradually increasing them. A few factors influence what will work best for you:
- Individual differences: Some learners retain information more easily and can extend the gaps sooner.
- Your learning goal: Shorter intervals help if you have an imminent deadline, but you’ll lose the information faster afterwards.
- Complexity: Difficult topics benefit from shorter initial intervals. You can stretch them out once the information starts to stick.
How many repetitions you need depends on the material and how long you want to remember it. There’s no magic number. However, the research is clear that five spaced repetitions beat ten massed ones for long-term retention. And with each successful recall, the next interval extends until the information is effectively “learned”.
The Science Behind Spaced Repetition
If you only remember one thing from this article, let it be this: spaced repetition is among the most robustly evidence-backed techniques in the entire learning sciences.
Six decades of cognitive psychology research point to the same finding. Spacing out your reviews produces dramatically better long-term retention than cramming. Here’s how the evidence stacks up.
| Study | Year | What they found |
|---|---|---|
| Cepeda et al. | 2006 | Meta-analysis of 317 experiments across 184 articles. Spaced practice beat massed practice in nearly every study. |
| Karpicke & Roediger | 2008 | Active retrieval (testing yourself) leads to substantially better long-term retention than passive re-reading. |
| Dunlosky et al. | 2013 | Reviewed ten popular study techniques. Spaced practice and practice testing were the only two rated “high utility.” |
| Voice & Stirton | 2020 | University of Leeds and Leicester physics study. Spacers scored 70% on exams versus 61% for non-users. |
| Carpenter, Pan & Butler | 2022 | Major review in Nature Reviews Psychology. Spacing produces benefits “of considerable size” across diverse learning contexts. |
| Price et al. | 2025 | Randomised trial of 26,258 practising physicians. Spaced repetition: 58% retention versus 43% without (effect size 0.62). |
Why This Matters
The strongest signal in the entire learning sciences is hard to argue with. From early laboratory experiments to large-scale randomised trials, spacing out reviews consistently produces gains of 15 to 20 percentage points on retention tests compared to cramming.
The recent Price et al. trial is particularly striking. It’s a randomised controlled trial of practising physicians (the gold standard of evidence design), and it found that doubling the number of spaced reviews produced even stronger results (62% versus 52% on later learning measures). The benefit held when tested more than a year later.
In other words: spaced repetition doesn’t just help you cram for tomorrow’s exam. It builds knowledge that lasts.
Why is Spaced Repetition Not More Popular?
For a technique with such a strong evidence base, spaced repetition is conspicuously absent from most corporate training programmes (and individual learning approaches). Why?
There are a few reasons, and they’re worth understanding if you want to introduce spaced repetition successfully in your organisation.
1. Cramming Feels More Productive
Psychologists call this the fluency illusion. When you re-read content or cram before a test, the material feels familiar, and that familiarity feels like learning. However, spaced repetition does the opposite. It forces you to confront what you’ve forgotten, which often feels uncomfortable and unproductive.
The research backs this up. Indeed, a 2012 survey by Hartwig and Dunlosky found that 66% of undergraduates regularly cram for tests. A follow-up by Morehead, Rhodes and DeLozier (2016) added an even more telling finding: 85% of students said they knew spacing was better for long-term retention, yet most still didn’t use it.
2. Time Is In Short Supply
According to research from Josh Bersin, the average employee has just 24 minutes a week for formal learning. With that little time, L&D teams understandably default to front-loading knowledge in single sessions, rather than designing programmes that revisit content over weeks or months.
3. Traditional LMSs Aren’t Built For It
Most learning management systems (LMSs) are designed for linear courses, not adaptive scheduling. Delivering spaced reviews requires either a purpose-built tool or a platform that supports algorithmic content delivery. Both are still relatively rare in corporate L&D.
4. Short-term Metrics Dominate
If you measure training effectiveness by end-of-course quizzes, cramming will always look better than spacing. Remember, spaced repetition only beats cramming on delayed retention tests, which most organisations never run. The technique looks worse on the dashboard, even though it’s working harder.
The good news is that none of these obstacles are technical. They’re cultural, structural, and measurement-related. Once an organisation accepts that retention matters more than completion, the case for spaced repetition becomes almost impossible to ignore.
What Spaced Repetition Unlocks for L&D
For organisations that embrace this mindset, the payoff is real. Three benefits stand out for L&D teams in particular:
- Knowledge Transfer: The Price et al. study measured not just whether information was retained, but whether it could be applied in new contexts. Spaced repetition produced a measurable advantage on both.
- Training That Survives: With so little time available for formal learning, L&D teams need to face reality. Short, distributed touches across weeks beat single-session marathon courses that nobody remembers a month later. The technique works with the time you actually have, not against it.
- Automated Personalised Learning: Modern spaced repetition platforms use adaptive algorithms that adjust review intervals to each learner’s performance. That means every employee gets a custom schedule without an instructional designer having to build 500 of them. The personalisation is automatic, and it scales.
Implementing Spaced Repetition in Workplace Learning
Sean Kang (2016) put it best: “Spaced practice is a feasible and cost-effective way to improve effectiveness and efficiency of learning, and has tremendous potential to improve educational outcomes.”
With this in mind, here are six practical tips for embedding it in your L&D programme.
- Campaign Learning: We know learning is not a one-time event. As such, you should seek to deliver training over time. You can do this by creating a learning campaign. For instance, you could start with an overview, then your content, follow up with additional resources and wrap things up with an assessment.
- Artificial Intelligence: Modern spaced repetition platforms use AI-powered algorithms to optimise review intervals for each individual learner. This scales personalisation across thousands of learners without manual configuration. AI doesn’t just space the reviews. It learns each person’s forgetting curve and adapts.
- Microlearning: Craft an engaging learning journey by breaking complex topics down into bite-sized modules. This will make it easier for learners to revisit your training in the future and enhance their knowledge. It will also help you to slot your modules into your learning campaign structure.
- Learning Management Systems: Platforms like learning management systems (LMSs) or learning apps can be used to automate the spaced delivery of learning materials. This can often be achieved by using Levels or Pathways functionality. Don’t forget to use reporting tools to optimise your schedule as necessary.
- Gamification: These learning platforms often enable you to use gamification elements like experience points, badges, and leaderboards. This empowers you to enhance your learner engagement levels while encouraging your audience to review information on a regular basis.
- Encourage Your Learners: As we’ve seen, many of us aren’t aware of the benefits of spaced repetition. With this in mind, consider providing your employees with resources and training on spaced repetition techniques. You should also encourage your learners to set up personalised review schedules.
Furthermore, as with any good organisational learning initiative, you’ll need to tailor your implementation plan to your learners’ needs. You’ll then need to gather feedback from your audience and make adjustments to your approach as necessary.
Final Words
Spaced repetition works because it aligns with how our brains work. Just like batteries lose their charge over time, we lose our ability to retain information without reinforcement. Thankfully, spaced repetition acts like a smart charger for our brain.
It delivers information in manageable bursts at strategic intervals. As a result, our beleaguered brains have the time they need to process, consolidate, and ultimately lock in that knowledge for the long haul.
For L&D teams, the challenge isn’t whether to do it. It’s how. Build learning campaigns. Let AI personalise the schedule. And train your workforce on the benefits. It’s up to you to make space for the technique that turns occasional training into knowledge that lasts.
So, say goodbye to cramming. And feel free to set a reminder to revisit this article in a week. Consider it your first spaced repetition session.
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Want to see spaced repetition automated at scale? Book a demo of The Impact Suite now. Hungry for more? Develop a deeper understanding of the science behind techniques like spaced repetition through our Guide to Learning Theories and Models.
