I've seen footage of John Shaw doing some amazing shooting, and he teaches to let your trigger finger leave the trigger briefly. I've started experimenting with the technique, but haven't adopted it yet. The theory is that it prevents shortstroking the trigger, but that's not something I've ever had a problem with.
The most important thing is to shoot smooth and only as fast as you can make hits. Speed comes from shooting slowly and getting progressively faster. Eventually, you condition yourself to reacquire the front sight and recover the weapon to the same approximate position, which speeds your shot to shot time.
I was training with some friends, who are also in the military and we were concentrating on shooting slow and smooth. A guy I knew from work was in the next lane, and he popped off five fast rounds, at 7 yards, which impacted from the target's shoulder to groin areas. He then said, "that's how it's done," and walked off. We did the only thing we could do, we ignored him.
The rythym drill helps too. Load all your mags with 5 rounds. Begin firing, and concentrate on reacquiring your front sight.
As far as accuracy goes, you should be as accurate as possible. I figure if shots groups open up during the stress of a fight, then the more accurate you are in training, the less they will open up during a gunbattle. If my "friend" shot all 5 of his rounds into the outside edges of his target (not watching the front sight), I figure they could easily be complete misses in a gunfight. Most of us have read of multiple rounds being exchanged at 3 meters and no one getting hit. Shoot only as fast as you can make accurate hits.
SMOOTH IS FAST!
[This message has been edited by Chuck Ames (edited October 21, 1999).]