I find I am very willing to experiment and improvise with shapes on small pinch pots. Somehow, on a larger pot, I feel some mental investment in making it come out the way I want---in not being disappointed with the result. Which is silly really, because if the form does not work, you can always just punch it down and start over! I often use small bowls to work through a form that interests me and they are the blank canvases for glaze combinations that show promise as a test tile.