That's a good average.... I'm usually around 20 feet after the leaves fall, sometimes 22 - 23.

Before the leaves fall, you're probably going to be forced to be lower because of visibility issues with the thick foliage. It all is dependent upon each tree, your whole situation, and available cover.

I took my best buck so far (162 1/8") when I was only about 9 feet off the ground, but I was in a tree that had a gnarly mass of tangled vines behind me which offered the perfect backdrop to help break up my outline.