that's fair enough. I just find that at top speed, with a pocket I come out on a much tighter line, and it avoids any possible ballooning out. Without a pocket, if they don't quite rate enough I find (expecially on the turn around the second barrel!) they will ballon out and it totally ruins their line to the last and takes sometimes up to 2 seconds.
But i've never ridden watern or a western trained horse, so it may be different as a lot of other things are.
Also, I don't put in a huge pocket, probably only half a meter?