commonguymd:
20-25 - 5% more yards
25-30 - 7.5% more yards
30-40 - 10% more yards
40-50 - 20% more yards
So a 100 yard shot would be 105, 107.5, 110 and 120.
Very close to what I use. 5, 10, 11.75, and 30 % in order.
Anyway (I may be wrong on this.) Keep in mind that each is a range. We don't know the exact coverage. I'd say using Commonguy's percentages as a low end, and mine as a top would get you pretty close.
There's also the rumor that about 2 months ago, WGT added some variety to rough conditions, so that we'd get a "flyer" every now and again. Adds some realism, especially now that the square grooves are being banned.