I try to never go above 20 because at that point the angle gets so steep that it becomes difficult to get both lungs.. I don't care for super steep shot angles.

I actually tend to hunt higher up in the early season. Now that there is no cover up there... I come down to about 15 feet or so to keep from being sky lined. If I have really good cover then I'll sit at 8-10... but that rarely happens.