Is there a relationship between finger pitch and thumb pitch? This is not the "increased finger pitch/span change" question... In other words, if I increase reverse finger pitch, is there any consideration given to "potentially" modifying thumb pitch if the span and all other factors are good?

I am old, but still pretty flexible.  For many years I used a 1/4 reverse in my thumb and 1/4 tuck in my fingers.  I based this on the old theories about how much reverse you should have in the thumb based on your span.  However those old theories did not address the current trend toward away pitches in the fingers.  What I have found is that, for me, maintaining a relatively parallel relationship between thumb and finger pitches allows me to maintain a similar feel even when I change the absolute pitches in both.  I now go 1/4 forward in my thumb and 1/2 away in my fingers.  My overall feel and ability to clear or not hang up has not changed.  However I am now able to create revs at the bottom of my swing going forward, rather than having to hit up from the bottom to create revs.

Like I said, no flexibility problems.  I could probably use any thumb pitch and not necessarily stay with the parallel relationship.  I did it totally to make it easier for me to achieve the change in release I was attempting to go to.