An awesome book, full of tips and ideas to organize practice to make it most efficient.
The central idea of the book is that practice does not make perfect, practice makes permanent. Basically, if you don't master a skill, by just practicing it poorly you don't get better at it, you merely get better at doing it poorly. You need to rethink practice so it becomes "perfect practice", which will indeed make you better.
For a coach, it shows how you have to understand the game, analyze it, find and isolate the elements of good performance, give them good strong names.
Feedback is an extremely important part of practice, so the book will show you how to most effectively use feedback, starting from practicing feedback itself, shortening the feedback loop and locking it in.
Extremely useful book, highly recommended.