Spacing. Reviewing a pattern just before you would forget it is what builds durable memory. It feels harder than re-reading, and that difficulty is the mechanism, not a side effect (Ebbinghaus's forgetting curve; Bjork's desirable difficulties).

Confidence matters. Mistakes you were confident about correct hardest and stick longest — the hypercorrection effect. That is why we ask how sure you are before showing the answer (Metcalfe).

Retrieval, not recognition. You have to produce the move on the board yourself. Picking it from a list only teaches you to recognise it (Karpicke & Roediger).

Interleaving. Once a pattern is half-learned we mix it with others, so you must first work out which problem you are facing — the actual skill you need over the board.