Ars Magica 5th edition says that "typically" a magus gains 2 warping points/year, which is a useful guideline to determine how many warping points a magus 50 years out of gauntlet has (the same number applies to Sahirs, from tCatC). However:

I noticed that the number does not quite match the numbers in Magi of Hermes, that are all over the place (even disregarding Twilight Prone characters). I was wondering: how did the authors of Magi of Hermes get those numbers?

How many of these warping points correspond to actual Twilights/Fatra Banya episodes (so that you can actually give an older character the appropriate number of such episodes), instead of single botches or exposure to powerful mystical effects? The way we do it, is simply say that you get one potential Twilight/Fatra Banya episode/15 years. You do roll for avoidance and possibly control/good or bad effects, and if it lasts longer than a week it "eats up" seasons, but any extra warping points you'd gain from it are assumed to be already accounted for by the 2 yearly warping points, and thus ignored. What method do you use? What method did authors of "canon" magi use?