I don't know how long it actually took the man shot in the back twice while running away to die. I do know from the reports it took George Floyd about 5 minutes to have no pulse though the industrious cop knee-necked him for another 3 minutes just to make sure. So did it take 5 minutes for bullets in back guy to die?
I guess unless you experienced you don't KNOW which is more painful though I suspect being unable to breathe is right up there.