One shot, one kill. Spray and pray is a good way to hit innocents.
Keep shooting until you are out of ammunition, or the threat is definitively neutralized.
No one said anything about “spray and pray”. I’m a good shot and usually hit what I’m aiming at. Rarely does one bullet stop someone committing mayhem. It may ultimately be fatal but usually the BG will continue functioning for several to many minutes. Even in the most effective caliber/round combinations multiple shots are usually needed to stop someone committing a crime or trying to kill you.