Even with PDF and PGN, players fail because of these errors:
The "Woodpecker" approach involves solving the same set of puzzles in increasingly faster cycles to program the subconscious mind. The Woodpecker Method 2 Axel Smith -PDF PGN...
If Book 1 was learning the alphabet of tactics, Book 2 is writing a novel. It targets players in the 1500–2200 range who want to stop missing those heartbreaking "one-move blunders" in tournament play. Even with PDF and PGN, players fail because