Single hardest thing to do in sports is to hit a baseball.
Players are taught to use the catapult loading system to hit.
The purpose of the system is to shorten up the swing for better accuracy to hit the ball square. Overall the greatest hitters have a compact stroke, although it is sometimes hard to detect.
The greatest hitting coaches were not the greatest hitters, they get paid millions.
I have taught this system.
For pool players, a long pretty stroke does not mean it is right. While I agree longer is better, I don't agree that long all the way through is the only way and best way.
The longer the distance the backhand has to propel mass, forward, and straight, the better chance it has to go off line. If you have a 14 inch bridge you do not need to pull back on the delivery stroke 14 inches for a smooth transition and get action on the cue ball.
Many top players with long, pretty preliminary strokes, pull back shorter on the delivery stroke, and it is smooth. They may have an 11 inch bridge and pull back 6 inches or less for delivery.
A smooth, fluid stroke comes from transition from back to forward delivery, it does not matter how long the bridge is, as long as you are not choking the chicken, even when choking it you can deliver smooth.
Last time this came up I referenced Alex, check out Lee Van Corteza playing in the 2014 world 9 ball and you will see, his is easier to see as it is more pronounced.
As for a herky, jerky, jab stroke, not too many people wanted any part of Alan for the cash, in all games.
Different strokes for different folks