I was just trying out the two-to-one and 1/3-more-than-twice systems last night on my Diamond (more recent even than blue label; it has a black label). I two to one banked fine for smaller banks (two diamonds or less total) but it started coming up short past that. Then for 1/3 more than twice, it was consistently short, just a couple inches inside the pocket every time. I changed it to 2/3 more than twice and that seemed to work for larger banks (3 diamonds+) but that additive constant started getting restricted below that.
Tangential, but how to most pros, particularly the ones strong at banks, approach bank shots? Given that very few in-game banks will follow lines perfectly, and so will require estimating angles and then contact points, and then adjusting for contact-induced spin, etc, etc, are systems really primarily for someone to set up in practice and see "what works" and then develop an intuition from there? Or are many players really just so adept at the various calculations and adjustments that they're doing the entire process quickly, albeit still consciously?