I personally don't even think about it, and I tend to shoot the comps quite quickly: at a guess, I'd say five to ten seconds between shots. I concentrate more on my stance and hold, and once those are sorted, I move on to sight picture. The Beretta 92FS is a heavy bugger, especially shooting single-handed, so once the gun is on-aim and I'm happy with my stance, hold and sight-picture, it stays on-aim until I have to reload.
Can't say I've noticed any major power drops doing it my way, so I suppose it's whatever works for you.
Fast-fire tin cans as fast as you can pull the trigger, now that's a different story: there's a noticeable decrease in power around halfway through the mag, but you'd never shoot competition targets that way anyway.
Hope that helps from my perspective.