Honestly, if a person is worrying about shooting through an enemy combatant, they probably won't shoot. They don't have the right mindset to do what is necessary to live, and their firearm may join the ranks of many illegal guns on the street. After the hesitant person gets shot first.
Self defense is like hunting in so many ways. You need to be aware, and react fast. The major difference is that instead of the prey getting away, you get killed/wounded.
With a SD scenario, we are the prey, and not the hunter. The criminal, the predator, has the time do the thinking. The prey only reacts when they realize the predator is there. That's why we have to be situationally aware.
homers brother stated the truth of self defense quite well. The right mindset will give you the edge to survive.