Most LEO's go through their careers never having to draw their weapon against a credible threat let alone multiple credible threats.
I personally don't want to be explaining to St Peter "well, I just don't get it. Statistics show there should have only been one attacker! Anyway, will you let me in through them pearly gates?"
Best case scenario if you get attacked is only one attacker, but getting attacked isn't a best case scenario. So I'm not planning for that.
A high number of officers are killed or wounded in a struggle over their own weapon or shot from ambush ,making the number of rounds in your carry handgun moot.
Or even the presence of it. I'm not carrying under the assumption I will be killed before I can draw or that they will take the gun away from me, I'm carrying under the assumption that I will use it in self defense if needed.