It's that 30-35 yards after the shot thing... That's probably time for another couple of shots and if it's running straight away, it's not going to be pretty.
It's pretty thick where I hunt, generally a bound or 2 and the cover has swollowed them up, very little opportunity for a second shot or third shot.
Practice, have confidence in your shooting ability, make the first shot like it's the only shot you'll get, and listen to him drop right after the cover swallows him up.
