For my part reading this thread there is more than one road to Rome. There are several calcs, and some I disagree with a bit more but I am old so get stuck in my ways. The key is though that any calc is a base calc that the individual is comfortable with, and can adapt around.
Merion is it's own special place so to shoot sub even 30 there on just the B9 you have to know the course. Some days the approaches all seem in place better than others and the bird putts are real chances, some days a bit of luck happens and an across face one drops, and some days may have well stayed at home:)
Mapping of irons with one preferred ball, as start point is essential. After that knowing how some holes play may also be necessary. As Ken alluded to it's about boxing clever sometimes on the green. No one normal expects to sink a 20 foot across face putt usually, but we can expect to leave it real close to walk away with no worse than par. Also and no disrespect here Ken as I appreciate you said you need to fudge (adapt) sometimes, and also sensibly looking to just be close I do agree with Mainz that those longer putts on V Fast look shy of the mark for any calc I have. Wind can make a difference, as can terrain (6 inches linear drop over 30 feet versus 27 feet then cliff edge etc etc. Go on for ages but in the end on V fast any calc should be getting you close with some common sense also.
Not being condescending JF, Ken and Pd or anyone hit me up anytime. If I can go round Merion "OK" any one can. It's about being able to adapt around basic calcs in my book, and all you guys have exactly the right attitude for that to happen easier than you may think.
People that can't / won't accept that, and think they can do it all with one definitive calc off the bat will still be having the same issues looking for the candy crush golden fleece this time next year and ...... There are many better putters than me (ignore some other fake 71% 1 putter's stats from Beth F9 only), but pretty sure I can help out any one genuine who has an issue with putting at Merion. Fine tune as much as you want after with loads of methods, but good enough for reasonable play.