Lesson
White to move. Main line: 1. Nf3+ Kd5 2. Bb3+ Ke4 3. Ke2 Kf5 4. Ke3 Kf6
A bishop only ever covers one colour, so mate can only be delivered in a corner of that colour. A defender who understands this runs for the wrong corner, and the whole technique is about not letting that happen.
The knight is the slow piece and it does the awkward work: it covers the squares the bishop cannot reach, which means it has to be repositioned constantly as the king is driven along the edge.
The tablebase says mate in 57 from this position. The fifty-move limit counts single moves for each side, so there is room — but far less than in any other basic mate, which is why this one is worth drilling rather than reasoning out at the board.