You determine his actions by using your brain and eyes together. I think I can see if someone is running away from me. I grant you that it is a hard skill to pick up just shooting at paper targets.
If one cannot determine if someone has his back to you and running out the door - well, not much can be done about that.
My point Glenn was that at any point in the confrontation the bad guy can turn and fire. Your suggestion is to surrender the edge in the conflict against an adversary who at any moment can turn and fire, bringing the possibility of death to you. I have to respectfully disagree. One thing is a bad guy armed with a weapon other than a gun. The gun changes everything IMO. I cannot risk a retreating shot or any other snap shot which with Murphy's law would hit me in the only unprotected vital area on my body. Further I cannot risk not firing and allowing the bad guy to regain confidence and reengage.
BTW, I don't only shoot still paper targets. I shoot still and moving paper targets of varying shapes, sizes, etc.. Steel of all shapes and sizes including movers. Probably the best of all, balloons, filled with helium they move erratically. I try to do all I can to practice other than at a still paper target.