And the risk of leaving an injured animal roaming in pain?
Should be about the same as that when a gun is used. Most bow hunters I knew were very disciplined about only taking kill shots because they were so worried about this very issue. I would guess that there are more animals wounded by guns than by bows in the US.
Bow hunters know that they have to wait for the perfect shot, too many gun hunters aren't really sure what the perfect shot is.