I have a 25 ft rope and I usually climb until I feel my bow come off the ground....this usually puts my feet anywhere from 25 ft or more.....but every situation dictates itself. Depending on foilage(canopy) and thermals I may go higher or stay lower....I will however tend to stay well above 15 ft.

Of course none of these answers says you can' t successfully take deer at lower levels...it' s all about concealment and movement....that' s why ground hunting can and will be successful...for me, hunting high allows me to get away with more movement than normal and I' m not a patient man when I want to draw.