Spacing
Is the same hour of study worth the same in one block as in four?
The idea
Review spread across time improves durable retention.
In the real world
Three short reviews beat one long cram session.
Going deeper
The gap between reviews is what makes each review do work. Retrieval after partial forgetting is effortful and strengthens the memory; retrieval while everything is still fresh is easy and strengthens it far less.
This is why the same ninety minutes produces different results depending on distribution. A single session keeps everything accessible, so each pass costs little and achieves little. Three sessions across a fortnight force reconstruction each time. The total effort is identical and the retention is not, which is unusual among study techniques — most trade effort for results.
Where it stops applying
Spacing delays fluency, so it is the wrong choice when you need something usable tomorrow. Cramming genuinely works for immediate performance and fails for retention.
Why it matters
Spacing your reviews changes how long the material lasts, at no extra total cost.
Try this today
Schedule a brief review tomorrow and next week.
Test yourself
Two people each spend ninety minutes on the same material. One does it in a single session; the other in three thirty-minute sessions across a fortnight. Same total time. Why do they not end up equal?
Show the answer
Retrieval after partial forgetting is what strengthens memory, and only the spaced schedule creates those gaps. The massed session keeps everything fresh, so each pass does less work and the whole thing fades faster.
Learn this in the feed Answering from memory, then again days later, is what makes it stick.