DarSum - Yeah, if you strike a 15' meter putt 50%, you'll get 7.5', +/- for green speed. I do use a homemade meter broken down into 5% increments. So, a 15' meter will go 7.5' at 50%, but a 30' meter at 50% will go 17-18 before green speed, a 45' meter will go 27-28, a 60' meter will go around 38-40' at 50%. A 15' meter, on a flat surface with normal greens, hit full will go around 18', but a 30' meter hit full will go 35ish or more, on up. If you hit a 90' meter 100% you'll get 110' or so. But you don't need the meter. If you think you can hit a shot right at 1/2 power, or 50% of the meter.
So, if I hit a 15' metered putt 7.5', if I switch to a 30' meter it should go 15', a 45' meter should go 22.5', a 60' meter 30', provided I use 50% and end my swing at the same spot for each. Obviously, uphill or downhill will change the shot somewhat, but on a relatively flat surface, the distances should be consistent.
To me, if I hit a putt 50% on a 30' meter, I am hitting twice as hard as if I hit 50% on a 15; meter, but I get more than twice the distance. Now, I know in the game there is a club movements, but that is a purely internet phenomenon. In real golf, it's a mathematical equation, and a putt hit twice as hard will go twice as far. Or to look at it another way, a putt hit 100% on a 15' meter should go the same distance as a putt hit 50% on a 30' meter. But in the game, if you have a 17' flat putt, and you hit it 100% of a 15' meter, it will drop with a foot to spare, give or take a few inches. If you hit the same putt at 25% on a 60' meter (which should also be 15'), it will run well past the hole.
For that matter, on a 15' meter, a shot hit 100% on a flat surface should go 15', before allowing for green speed. But it doesn't. It will go over 15', regardless of green speed, on a flat surface. In this particular case, it is inconsistent math. But math is a purely fact based science. If your math isn't consistent, neither will the shots be. The game's math is inconsistent, and my suggestion would be to make it consistent.
There's also a reason I put that last. Gimme a putting green to figure out the inconsistencies, a driving range, and fix the fringe, and I'll deal with the inconsistent math.