Middlegame tactics often allow for "good enough" moves. In the endgame, one tempo (one move) means the difference between a win and a draw. Puzzles train you to calculate with absolute precision.
Many national chess federations (like USCF or the English Chess Federation) release free training booklets. Search for "USCF endgame booklet PDF" or "ECF endgame puzzles." chess endgame puzzles pdf
Go back to puzzles you solved incorrectly 7 days ago. Use a flashcard app (Anki) to import the diagrams. The PDF acts as your master database. Middlegame tactics often allow for "good enough" moves
