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!!