To my knowledge, NEVER. If I pass a buck, I could careless if it gets shot 3 seconds after it leaves me. I don't pass in hopes that it will live long and grow big. I pass because of the deer that are roaming the woods at the time I am hunting that are big enough for me to shoot. Also the few times I was hunting a particular buck I either killed it or it was never seen again/killed by someone I don't know.