As a scorer you are going to get different types of shots throughout the course of a game. Some may be off the dribble, off the catch, using a screen, etc. It is important that you are comfortable with these different types of shots and are able to capitalize on each of them.
This shooting drill is going to work on 3 different types of shots all in sequence. All of these shots will occur regularly throughout the course of a game, and this drill will help the player master each type of shot. It is also a great drill for staying mentally engaged as you get tired. By having multiple sequences that the player must do, it forces that player to stay mentally locked in throughout the drill.