Recently I made a mobile whose design incorporated the very difficult art of vertical balancing.
Afterwards I reached different conclusions. First, vertical balance has no value for an average viewer. Even when it is pointed out, he does not appreciate it. So 3 out of 7 nodes of my mobile were not adding any value to the average viewer.
The balance four were just not moving relative to each other. but were rotating in a plane. Very boring movement with no re-carving of space.