Good suggestions. I do keep notes about what I do but have not done such extensive tests as you have done.
My FP4, HP5, and Tmax 400 developed at this lab have been turning out fine as I have been exposing them and how they develop.
It's just that I have never used Delta 3200 before, so I need to figure out what's going on re my exposures and their developing for that film.
I may not even use Delta 3200 much in the future. I have a couple more rolls here, so I want to do my best with those. But, unless I really fall in love with the Delta 3200 look, I'd probably be better off just pushing HP5 if I need ISO 800 (for example), because of the extra cost of the Delta 3200 and extra developing cost.
Thanks for typing such a long response! You are so right about the many variables when shooting film.