Here is my theory as to why I use the "off the ding" method....
I am Champion Tier with a 58.17 average currently.....so I consider myself a very good WGT player though certainly not in the elite class of players on here.
The ding method
You need to do 3 things correctly using this method.
1) Distance
2) Where you move the arrow
3) Hit the ding
The off ding method
You only need to do 2 things correctly using this method
1) Distance
2) Stop the meter at the right spot to compensate for the break
Now, while there really is no mathematical algorithm to calculate where to stop the ding, you also don't have to stop the meter at an EXACT location. I believe there is a range where the meter can be stopped in that will correctly compensate for the break off the putt. So there is some margin for error.
So how do you know where to stop the meter to find that successful range ? It's mostly just a feel that is gained from experience and practice. Since I believe that WGT tweaks the greens at cyclical times and that the successful range on the meter can change, you probably should do a few practice holes to determine how much play area you have with that day's meter.
For example, unless the dots are moving very fast or very slow, on my first putt of the day I will use the mid-point of the hitting area of the meter to compensate for the break. If the putt goes in or comes very close to dropping, then I know I pretty much have a little before and after the mid-point to have a good chance to have the putt drop when the dots are moving at what I consider to be normal speed.
If the dots are moving slower or faster than that I will compensate by stopping the meter sooner or later than the mid-point to compensate for more or less break.
Of course there are some putts that I will have to move the arrow off the hole simply because there is not enough meter hitting area to compensate for the crazy break.
I'm sure that's all clear as mud....lol