Tried it albeit briefly, but more than 1 hole MM LOL
I intentionally used it on putts with BIG breaks mainly...
It works to a point, as do several other methods, but like "all" the others it requires you to make adjustments according to the situation you have ...
Like the others it is a guideline, a starting point, not an exact science...if you can't putt well you will see a vast improvement because most putts on WGT are within the parameters of this method...if your already a good putter you won't.
I was looking for something that would be more exact on long or shortish putts with breaks bigger than a full grid box...of course the best solution is hit the approach shot stiff and on the correct side of the pin LOL
What I found was on most putts the aiming point is almost identical on all 3 methods I tried for comparison on almost all of the putts.....one of those happens to be 10 times faster than this one.....
Also it seems to work better on faster greens, not so much on slower greens which would be expected, I only tried it twice on fast greens and that of course would be one of the adjustments I mentioned...
Like josh said, when you get used to it it doesn't take as long, much like g0lds method which is similar, but still a lot of time...like all the others, on it's own, it will make you a good putter, but not a great one.