Angle makes all thedifference. You bullet flight will drop based more on horizontal range travelled, not verticle. You could be shooting 100ft up into a tree or up a bank, but your bullet might only be traveling 20 feet horizontally, so if you held for 100ft you would over shoot. For coons I would zero at 25, but practice at 10yard intervals from 5 to 100 yards. If your using a 22lr your ammo will be cheap enough to let you practice allot.
A red laser works great for nighttime coon hunting as well, especially if you are hunting with kids, it letsyou know where they are aiming and help them sight on the coon.