I have an affectionate nickname for those players using a putting formula. I call them "rocket scientists." It's fairly easy to spot them in Stroke Play. Here's how:
They all have a tier ranking greater than Tour Pro. Player A, a Tour Master, has a 27.6 ft. putt on a tourney 12 green. It breaks moderately to the right, and is downhill by 17 inches. Player A, whips the calculator into a number crunching frenzy that goes something like this: "the moons gravitational pull divided by the number of days past the vernal equinox times the dimples on a Titleist ball minus the wing velocity of an unladen sparrow plus the square root of the current relative humidity.... yada, yada." He makes a list, he checks it twice. Then, he consults a spreadsheet after consulting a spreadsheet after consulting a spreadsheet. He double checks his spreadsheet using a homemade C++ computer program. 87 seconds into the second 90 second timer, he's ready. He's got this. It's going down. He pulls the plunger.... he releases.... AND HE STILL FREAKING MISSES THE PUTT!!!
Here's MY putting formula. It's a 27.6 ft putt on a tourney 12 green. It breaks moderately to the right, and is downhill by 17 inches. I look at the read carefully. USING ONLY MY EXPERIENCE AS A GUIDE, I'm ready. I've got this. It's going down. 7.37 seconds into the FIRST 90 second timer, I pull the plunger.... I release..... AND I STILL MISS THE FREAKING PUTT!!!
MORAL OF THE STORY: I can miss a putt in 1/10 of the time it takes a "rocket scientist" to miss a putt. And, I can still finish a round under par NOT using a putting formula. (PS- I'm pretty darn good just eyeballing my putts. Why? Because I'm not a slave to a formula.)
If your putting average is below 95% using your putting formula, I strongly suggest not using it in a Stroke Play game. You turn a half-hour 9 hole round into a one-and-a-half hour nightmare. Stop it. There's no money, real or virtual, involved in stroke play. Be considerate to other players. Show some class. Speed your play up. Save your formulas for the money games and tournaments. Use Stroke Play to hone your NATURAL intuitive gut feeling skills. It takes practice, but it works, trust me. Besides, that's what you did when you first joined the game. So, do other players a favor and take a nice long walk down memory lane and get in touch with your inner newbie again.
I'm sorry, but I've become increasingly frustrated by the painfully slow pace of the rocket scientists in Stroke Play. I absolutely cringe when I get stuck in a foursome with three other rocket scientists. It blows chunks. If you need to practice using a putting formula, do it in a solo game. You guys take yourself way too seriously and take way too long for a game option that yields no money, no fame and no late-night talk show appearances. Just hit the flippin' ball, it's not rocket science.
In my opinion, the best putting formula is a solid approach shot. Learn to consistently nail it 15 feet or less from the pin, and you won't need a putting formula. It can be done.