There is no magic formula for putting.
Forget grids, in fact they're only needed to ascertain whether the slope is at 90 degrees to the hole or not. A slope that breaks 90 degrees will break more than one at 60 degrees.
Dots are more important than the grid.
Green speed and elevation must be taken into account which effects how much the putt will break.
This debunks any notion that there is a magic formula for all putts based on a grid. To suggest or think otherwise defies the laws of physics.
Essentially, buying into the idea there is a magic formula based on the grid divided into set figures is ridiculous, and a waste of time messing with. The Tooth Fairy and Leprechauns exist too..
The only formula one needs to know is how far your putt will roll over a given distance and elevation according to green speed and break.
Once putt weight calculation is settled then the fun begins. Read the line and picture the ball moving along the putting surface to the hole at the speed the putt is hit.
Always check the line using chip.
Be the ball