Ray, heres my thought. The back of the bow should be parallel with the archer. The grip style dictates hand position, high low wrist, more or less palm. If you set the bow on your tree with out the shim, once tillered you'll end up with a stiff upper limb (think I'm right). So the bow will want to tip out of your lower hand and towards your head. I might be backward on my thinking, still half asleep. But i would leave the shim.