Comment by creature_x

I built a Chess app called SpicyChess(https://spicychess.com) that has a training component which leverages spaced repetition and strict time constraint to increase your pattern recognition ability for tactical motifs. SpicyChess also allows you to "bookmark" a puzzle for review later on. The philosophy behind the training regiment is inspired by the following two books which have been very helpful in improving my game: reading Rapid Chess Improvement, The Woodpecker Method.