I just started hunting last year, I could have had one, but I waited too long for the "perfect" shot and he got away.
I do some "trick" shooting, and would have most definitely been able to hit that deer at his brisk walking pace, but I was with my neighbor who I had never hunted with before, and didn't want to look like a show off jack-end by shooting a briskly moving target.
Lesson learned, and that definitely won't happen again.