i don't believe any shot or every shot is a garauntee "drop'm in their tracks" shot. i've seen deer shot in the head run 100 yards before falling. i've also seen heart/lung shot deer run. the closest to a "drop'm in their tracks" shot is a spine shot and even these don't mean a quick kill.

the most important thing is to make the most humane shot possible, this way the animal does not have to go through any unnecessary suffering.