I don't change my aim point either but shooting from a sitting position directly in front of you or at an angle to the left or right can pose a real challange if you haven't practised.Add all your rigging and the awkward shot and bowhunting takes on a whole new face.Ron

I agree with CLOUD9, MN. The only way to be 100% sure is to shoot from your stand height before the season begins. Also, I carry some practice arrows with me on my evening hunts. When I get situated in my stand, I pick a small leaf to shoot at and shoot one or two arrows. This does a couple of things for me. First, it gives me confidence. I don't always set up the same stand height,(it depends on the tree, terrain, etc.) and shooting a couple drowns out any doubts I may have about any shots. Second, it gives me a chance to correct any problems I may have with my stand. For example, how many time have you gone to pull back on a deer, only to have your elbow hit the back of the tree, or have a limb resting on the top of your bow? But I believe the most important thing about shooting from the stand is knowing that your equipment works!!! I remember some practice shots I took from the stand that were nowhere near where I was aiming!!! Turns out that either during transportation or the walk to the stand my sight had come loose(maybe it got caught some brush??) and I was way off!! I don't want to think about what would have happened if the monster buck was standing broadside at fifteen!!!
Anyway, that's my two cents!!

The only difference between shooting out of a tree and shooting from the ground is the way you hold your bow. Make sure you bend at the hips and keep your arms in the same position as you do when you practice. If you study physics it doesn't matter the actual distance the arrow flies, just the horizontal distance as to how much it's going to drop. So just bend at the waist and you'll do fine, good luck hunting!