One of the best sporting/FITASC shooters in the world will tell you that he never fires until he can clearly see the rings on the bird. If his shot is 55 yards instead of 40 so be it. He's confident that if he can see the rings, he can break it regardless of distance, angle, or other factors.
Of course, another world class shooter once told me that the sooner you can break a target off the trap the better.
Find out what works for you and go with it. In trap I shoot fast (as soon as I see movement). In sporting/FITASC I mix and match depending on presentation.