I personally use 3/8 reverse and 1/4 left lateral on my thumb. I have a stretched fingertip grip and am right handed.
I used to use a touch shorter span and no reverse, but I stretched my span just before semi-dislocating my thumb (wrestling with a buddy of mine). After that, I could not clear the thumbhole without a bit of reverse, not even with the shorter span, so that is where the reverse came into the game for me.
True, I do need the thumbhole to be QUITE snug to keep from losing it early, causing much callusing of my thumb, but I have become used to it and use a pumice board to keep the callusing worked down.
The pros get out of it that good because they have their balls drilled to their own specs that work for them, NOT because of some gimmicky, trick drilling. They want to control their release, not just dump it with revs at the line due to excessive reverse in the thumb.
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