Greg, this is a highly subjective question.
If a hit is made to the central nervous column (spine, brain), then there are numerous instances of one-stop kills. This is highly reliant on all the right variables being in place - shot placement, angle of entrance wound, penetration, velocity, expansion.......
No two shootings are ever the same. Count on multiple rounds placed to COM (centre of mass) for the best overall results. In other words, you keep shooting until the target stops doing whatever made you shoot him in the first place. Some will die before they stop doing whatever they are doing. Methamphetamines will often negate any pain factor that a BG will feel. You may need to empty a full magazine (or more) before you stop someone who's doped up. Others with low pain tolerance (and no chemical pain inhibitors) will give up after a flesh wound.
Nothing is guaranteed in a shooting. There is, for all intents and purposes, no such thing as a one-shot cartridge. There are only instances of one-stop shootings, when all the variables (including luck) add up occasionally.