The racking knowledge is probably the most popular but Guaranteed Improvement and the Aiming Workout get me my best results. I think any player who commits to these drills will be happy with the results they see. Anybody can make up a drill but Joe has come up with drills that are directly geared towards developing a consistent high level of play. His score keeping concept makes it easy to track results and see what areas of your game need more work. No blowing smoke or sugar coating with Joe! Just productive drills that will help anyone improve and have fun in the process!