Spaced repetition

Spaced repetition distributes reviews over time instead of placing them back to back. The learner tries to retrieve an answer, receives the solution, and meets the same material again after a delay. Separating study sessions generally produces more durable retention than massing all repetitions into one session.

Intervals can adapt to performance. An item recalled easily returns later; an item forgotten or answered uncertainly returns sooner. There is no universal schedule because a useful interval depends on difficulty, response history, and how long the knowledge needs to be retained.

Application to chess

It can support recall of opening replies, critical positions, recurring threat and capture patterns, late-game procedures, or board coordinates, the letter-and-number names of squares. Review works best when it requires active retrieval, meaning an attempt to produce the move, plan, or explanation before the answer is shown. Passively recognizing an already visible solution is a weaker test of memory.

The system preserves information, but it does not create understanding by itself. Every review item or position should include a reason: what threat exists, what plan the move serves, or what error it prevents. A memorized sequence without that context can collapse at the opponent's first deviation.

A drill defines the task being practiced; spaced repetition defines when that task returns. It can also schedule mistakes found through self-analysis, an independent review of one's own game, or an opening trap, an early sequence that punishes a tempting reply, that was forgotten during play.