There are specific shots and moves that you are going to use during the course of a basketball game. This basketball drill represents a game situation shot that you will use during the course of a game, and the goal is to get the player a lot of reps at this particular shot. That way they are comfortable shooting it in a game.
Shooting a regular catch and shoot from the free throw line has a different feel than shooting a post flash shot. That is why you need to practice flashing up for the shot at game speed. You will probably use this shot when playing against a 2-3 zone, or if the opposite post just decides to flash to the high post and their man is a few steps behind. Post players can add a lot of value to their game by being able to consistently knock down this type of shot.