The knight's unique L-shaped movement makes it the most challenging piece to visualize. Practice calculating knight jumps in your head - a skill that separates good blindfold players from great ones.
Pro tip: The knight moves in an L: 2 squares in one direction, then 1 square perpendicular.
A knight is placed on the board and you have 60 seconds to mark every square it can reach. It is the drill most players find hardest and skip, which is exactly why it is worth doing: the knight is the only piece whose reach cannot be traced along a line, so it is the piece that breaks a mental board first. Miss one knight square in a blindfold game and you do not lose a tempo, you hang a queen.
The reach depends entirely on where the knight stands. From d4 or e5 it hits eight squares, from the b-file or the second rank six, from a corner only two. Learning those counts is the fastest way to stop miscounting: if you have found five squares from a central knight you know to keep looking. The second anchor is colour parity, a knight always lands on the opposite colour to the one it left, so any candidate square of the same colour is wrong by definition. Once the map comes instantly, take it into pathfinding with the knight maze, or apply it to threats in attack detection. If square names still cost you time, go back to coordinate training first.