Is there any significance to my body motion observation?

I am sure that I am not the first to notice this, but I have never come across anything on it, so here goes.

Raise your hand to shoulder level. Keeping your arm relaxed, let it drop until it comes to a natural stopping point. Let it drop again until it comes to a stopping point. If you try this a third time there will be no stopping point. If you try to keep your arm raised between stopping points, you will find that it takes much more effort.

So my question is, is there any significance to this? It would be of interest to know what the stopping points mean anatomically. My belief is that all moving body parts have stopping points and that they help us move smoothly and accurately. For example, if you throw a ball the various sections of the arm will move to their stopping points.