What I have found in my many hours of practice on the putting greens recently is this:
For putting breaks, I use a factor of 2.8.
Distance to hole...if uphill subtract the distance in feet. If downhill add the inches in feet.
For instance. If it is a 5 foot put downhill 1 inch. The total is 6. Then divide 6 by 2.8=2.14.
That is the amount of holes to move either left or right.
2.8=4 seconds for the dot to move across the grid.
So, now for a 5 foot putt there should be 2 grid lines, if each dot takes 4 seconds to go half way across the grid then it would be 6/2.8=2.14 holes to the right or left.
But, if the speed varies for both grids. lets say 4 seconds and 2 seconds which equals 6.
If they both moved at 4 seconds that would be 8. So now I divide 8 by 6 and get 1.3.
multiply 1.3 by 2.8 and you get 3.6. Now move the marker 3.6 holes left or right.
LOL. Not sure if I explained it right.
Happy Hitting.