I recently made a fit change. I extended my span to 4 7/16, but didn't change my thumb pitch. I was using 1/4" fwd and 0 lateral. I started rubbing on the side of my thumb, thus I added 1/8 palm. Since doing so, no rubbing and I'm clearing the ball pretty well.
For blank drills, I ask customers to pick up a pencil and see if the thumb goes more towards the middle or ring.