Spaced repetition is one of the most replicated findings in learning science. Here's what it actually is — and what it isn't.
Takeaways
Review at the edge of forgetting, not when it feels comfortable.
Let intervals expand as confidence grows.
Many short sessions beat one long one — every time.
Why timing is the whole game
Memory consolidates hardest when retrieval is effortful but still succeeds. Too easy, and the brain files it as already learned. Too late, and you're relearning from scratch.
Good spacing systems aim for that middle zone — where you struggle, succeed, and move on.
A practical rhythm
A workable starting point: review within a day, then after three days, then one week, then two. Intervals should stretch with mastery.
Miss something? Shrink the interval immediately. Getting honest about misses is what keeps the system sharp.
