Ability to hit what you want to, with what you carry?
You have to put all focus on the small 1 inch spot of hair you are going to place your shot into.
I have met Dave Grossman on more than one occasion, he is very bright. I am a Retired (are we ever) firearms instructor.
When I teach Police, I have a Scenario I always insert.
Based on the most dangerous call, of all. The Domestic! First we establish (class participation) the average size of a kitchen. It normally is about 6m doorway to the corner of the counter, where the knife drawer/block is. The CALL! Man with knife, holding woman, in front of him, you can see his eye, and nose.
I state, the eye socket is a good place to hit. Feel your own, just under 2". Target is an IDPA cardboard one. One each. I draw one left eye, next, right eye, on each head. Moving along.
"Draw and aim at your individual eye!" "Shout very loud" "Drop the knife" three times.
"Then fire the shot in your own time."
This is their duty weapon. This exercise is shot cold! The hits, are normally absiminal!
The class is now about fixing that!