Interleave your review, not just your first pass

Review old topics mixed in with new ones instead of reviewing each unit in isolation.

Why it works

Reviewing one unit at a time recreates blocking at the review stage, letting you coast on still-familiar material. Folding old topics back into the current mix forces retrieval of things you have started to forget, which is precisely when retrieval strengthens memory most.

How to do it

1. Each session, add a few problems from earlier units into the current mix.
2. Prioritize the older topics you can least reliably recall.
3. Keep the share of review high enough that nothing fully fades.

Evidence

Mixing prior material into current practice combines interleaving and retrieval practice, both well-supported effects: retrieving partly-forgotten information produces stronger long-term retention than re-reading it while still fresh. (rct)

This is an application of established interleaving and retrieval findings to the review stage; the staged-review format itself is less directly tested than the underlying effects.

Common mistake

Treating review as a separate, single-topic block done right before a test, which feels reassuring but skips the harder, more useful mixed retrieval.