Your theory is all good and well if you are law enforcement chasing after felons, and your job is to engage them.I never understood this type of thinking. Basing your EDC gun and spare magazines on the average shooting leaves out the "other" types of shooting incidents that will get you killed. I always live by that adage "Pray for the best, but, plan for the worst." If you're prepared for the worst case scenario you will be better prepared to survive than someone who only plans for the best case scenarios. In most cases one shot will usually stop an aggressor. But, in worst case scenarios, even large caliber handguns have not stopped an attacker. And then what do you do if there are multiple attackers?
There are plenty of incidents where an attacker had been shot multiple times and continued their murderous assault. The 1986 FBI shoot out with the armored car robbers Mattix and Platt in Miami is one example that comes to mind. I'm not saying that you would be trying to stop and arrest such dangerous individuals. I am saying that in the event you unintentionally encountered such individuals and needed to use your EDC handgun to defend yourself, that your 2.3 rounds fired at someone like that isn't going to do anything other then get you killed. Especially If your life saving plan is to expect to only need to engage in a quick 2.3 shot incident. One of the FBI survivors of that Miami shootout, Special Agent Mireles, stated on a training video that the one thing that he learned that day is to carry as much ammunition for reloads as you possibly can.
The pivotal term I use is to "Engage". That makes all the difference in the world as far as planning for the worst and praying for the best.
In civilian self-defense... the name of the game is not to engage, but to avoid criminals. Hence, any gun, even a 5 shot snubby is better than being unarmed. I don't live in an open carry state, and so to me and other civilians, we are bound by the CCW laws to carry the smallest or rather, the largest most powerful weapon we can conceal without printing, or lest we could be charged with unlawful display of a firearm.