Spaced repetition:
short and often beats long and once.

The forgetting curve

Back in the 19th century, Hermann Ebbinghaus showed that we forget new material especially quickly in the first few days. Each review flattens this curve: the material sticks for longer afterwards, and the next review can come later.

What research says

The spacing effect is one of the most robust findings in learning psychology. A large meta-analysis by Cepeda and colleagues (2006) pooled hundreds of experiments: spaced learning beat massed learning almost across the board. In the review by Dunlosky and colleagues (2013), it received the highest rating of all techniques examined, alongside practice testing.

A simple review schedule

You don't need software to start. A rough rhythm is enough:

• Day 0: work through a chapter and answer a few practice questions right away.
• Day 1: recall briefly without looking at your notes. Look up the gaps.
• Day 3 to 4: redo the chapter's practice questions and mark the wrong ones.
• After one week: only the marked questions plus a few mixed ones from earlier chapters.
• After two to three weeks: a trial run with questions from several chapters.

Mix instead of blocks

Mixing questions from different chapters instead of finishing one topic after another means you first have to recognise what each question is about. That is harder, but it prepares you better for exams, where questions aren't sorted by chapter either. This is called interleaving.

Tools

For facts and terms, apps like Anki do the scheduling for you; more in KnowFi vs. Anki. For understanding, past papers and problem sets work well. With KnowFi you see at every review why an answer is right and where it is in your notes.