One of the most common things among top pros, for the forehand and two handed backhands, is to follow through upwards but across the body, ending up near the opposite shoulder.

This has the advantage of creating natural topspin, a necessity at the high speeds of the professional game.

The straight follow through, which is advised by conventional teachers, actually flattens the stroke and increases the risk level.

Another advantage of going across the body is that by bending the arm more muscles act up and connect to the main trunk of the body.

The end result is more ball speed with less racket speed, which adds to the control of the shot.

It is much easier to control the angle of the racket at slower racket speed.

Bending the arm you don't sacrifice the velocity of your shot to get the ball in the court.

The opposite is truth for conventional players, who follow through towards the target. When in trouble, they need to slow down the swing to keep control of the shot.

And mostly, because of the brushing of the ball when you go across, you'll have more feel and more control, no matter how hard you hit it.