I have played seriously with FA's than most people who don't actually own one, mostly by luck and circumstance. FQ to answer your question in my opinion, you would be much better off, making 3 single hits, given the platform you suggested, on FA, caliber and type do matter, I have shot the all american 180 22rf, squirt gun, tons of fun, like peeing in the snow, you can hold it on target ( even a novice ) until it runs out of ammo, kind of like shooting those old gallery Thompsons that shot lead BB's at the fair, M16's, AK's in 7.62x39, G3's in of course 7.62x51, MP5's, Glock 18's and Beretta 93r's, the MA deuce of course is not part of the consideration here. I shoot them well, but if in normal situation, would not hit the FA switch, UNLESS, I want 1 sumbitch dead right now, and it has to be quick. I can put a fist sized hole of 32 rds from a MP5, one continuous burst on a IPSC target at 15 yards, that takes about 1 1/2 seconds, without reaction time, why would I do that, unless, I really want that guy dead, and I expect no body else to be firing back at me. You can make more accurate hits faster with 1 shot or a controlled pair, on MULTIPLE targets, IHMO, than with a most FA's. The larger and more energetic the round, the harder to control. If I was on the street, and had to make a decisive shot up close and personal, that Glock 18 will be wonderful. If he's got 2 or 3 buddies, not so much. If it is full auto time, I want a belt fed and a good position to shoot from. 30-40 rds sounds like alot, until a second and a half later, its empty. In controlled shooting, 30 rds ought to get you the hell out of there, with probably some coroner showing up to give time of death.
The 3 round burst deal came up to reduce wasted shots, not to encourage accuracy.