Every pro pool player I have ever heard of says that a long follow through is key to playing good pool.. It is also the key to good golf strokes, good batting in baseball, good shooting in basketball, bowling, javelin, discus, shuffleboard, etc.
It seems to me that the longer the follow through in any sport, the better. In a golfer's swing, the follow through continues until the club shaft lightly taps the player on the neck or shoulder, (I'm not a golfer) if I am not mistaken? The follow through continues until it is physically impossible to follow through the ball any more. Doesn't the same thing happen with a good baseball swing? I would assume a perfect bowling swing realeases the ball at the last possible microsecond before the bowling ball reaches too far in an upward arc. In a basketball shot, the hand supports the ball while the arm supports. The "follow through here is the proverbial "wave good bye", again, the hand follows as far through the basketball as possible.
Russ