I was just at a pro shop and they had some fitting instructions from a recent IBPSIA class. I noticed that they are not using the fitting tubes for the thumb lateral pitch, but using a different thumb hinge method where they just push on the base of the thumb and see where the thumb points to as it bends.
The picture on the instruction shows the top nail of a hinged thumb when testing. When I do this test, I only see the side, to almost bottom of my thumb. The Bill Taylor method(coke can/fitting tubes) has my thumb pointing well past my pinky. They reluctantly only put me at 1/4 right in my thumb. I'm currently at 3/4 right, and feel I actually need more.
I feel that this fitting method is inferior to how it should be. Yes it might work for 80 to 90% of the bowlers that have "normal" thumbs, but it will not be effective at determining the true pitch that is needed.
I feel that most fitters get the thumb pitch wrong, and accommodate the wrong pitch with a loose thumb hole at the top, or having to use excess bevel so a bowler does not hang up.
Right now I'm 4 7/8 span with 3/4 right and 3/4 reverse. I'm using a vise thumb oval that fits pretty snug, and I have zero bevel or shaping on the thumb. I only smoothed out the edges so that it wouldn't cut my thumb at the top of the hole.
Just wondering what people think is the best way to find the correctly lateral thumb pitch.