I go anywhere between about 8 and 16 feet. Depends mostly on cover. I don't like the steep angle of shots higher than that, and I can usually get good cover where I need it within that range of height. I use scent killer, carbon clothes, etc.and rarely get busted. When I do get busted it's almost always been because I didn't see a deer and moved in late firearms season when they're extra paranoid.

Doesn't going much higher than 20' make it hard to double-lung them?