I don't like to directly contradict anyone, but I can't let this stand, because you're giving a very dangerous impression here. Yes, YOU may fire your carbine with the stock folded all the time, but-
BUT! The stock should ALWAYS be used if it can be. It lends additional speed and control, even if one doesn't have time to even actually use the sights. It still allows faster hits, at anything over contact distance range. Don't take my word for it, talk to the experts. In fact, a number of them are mods or members here. Feel free to bring this question up with Jeff White, Art Eatman, Larry Correia, or Zak Smith, to name just a few. Don't hesitate to pop back up and let me (and everyone else) know if any or every one of them suggest shooting with a folded stock if you have the time to unfold it.
John, not an expert, but thousands of rounds fired in Stressfire close-range training.