I have a 16' ladder stand that I always practice from in the backyard. This way my pins are set up for game time (meaning a hunting situation), not practice time. Iput outa block target or two and use my range finder just as I would in the woods. I personally feel like it's a way to remove one more variableI would haveadjust for when tension is running high, and I've had great success since doing so.

What you're talking about is also the theory behind penudlum sights I believe. The mechanics of the sight compensate A^2 + B^2 = C^2

Just as Wis Bo Huntr said, you need to aim a little lower when shooting from a tree with a bow that is sighted in on the ground. How much or how little depends on the setup, your height above ground, your target's distance away, etc. By sighting in from a tree, and practicing from a tree, all I need to do is worry about my yardage, not my yardage, and then remember to aim a little low... no, no, no, still a little lower.... sh*