Spaced Repetition vs Cramming: What the Research Shows

Spacing beats cramming. Studying the same material in several sessions spread over days leads to better long-term memory than the same amount of study packed into one session. This is one of the most replicated findings in learning research.

The evidence

A 2006 review by Cepeda and colleagues pooled 839 comparisons from 317 experiments on spaced versus massed practice. Spaced study won, and the best gap between sessions grew with how long you need to remember: for a test tomorrow, a short gap is enough; for something you need in a year, the gaps should be longer.

For flashcards specifically, Nate Kornell's 2009 study had people learn vocabulary pairs either in one large stack (each card came back after a long gap) or in four small stacks (each card repeated quickly). The large stack won for 90% of participants, and it also beat cramming the day before the test.

Why cramming feels better anyway

In the same study, 72% of participants believed the small stacks had worked better. Cramming feels productive because the answers are fresh, so you get them right during practice. That ease is misleading: being able to recall something one minute after seeing it says little about recalling it a week later. More on this in why studying feels harder when it works.

When cramming is fine

If you only need something for a test tomorrow and never again, cramming the night before works for tomorrow. It just doesn't last. For anything you want to keep, such as a language, spread it out.

How spaced repetition automates spacing

Doing spacing by hand means tracking when you last saw each card. A spaced repetition scheduler does it for you: each card you remember comes back after a longer gap, each card you miss comes back soon. How spaced repetition works in Decks shows the exact intervals and the full references.

References: Cepeda, N. J., et al. (2006). Psychological Bulletin, 132(3), 354–380. doi.org/10.1037/0033-2909.132.3.354. Kornell, N. (2009). Applied Cognitive Psychology, 23(9), 1297–1317. doi.org/10.1002/acp.1537.