What I don't know is how this formula changes for fast, average and slow trainers. I believe it is for the average trainer. And those are not the players who people have historically power trained for roles and SAs.
Another thing I don't know is how to tell a fast trainer anymore from his training/match improvement results. The only thing I can go on is the ratio of value to salary for brand new (academy and nordgen) players. But looking at who gained how much, I am really just guessing who is a fast trainer and who isn't. In the old system a fast trainer would gain about 80-100 in a competition match. If I understood the point conversion, that would translate to about 4% gain now. Most of my players gain more than that: 5-6% in a competition match, so either my math is off, or all players became more trainable just like that.
And as far as gain from drills, I have no expectation and no way to gauge progress. Sometimes a % gain will pop up, sometimes it won't. I think the gain from drills in cumulative, too. If you run the same set two times in a row, and there is no gain from the first set, but plenty of gain from the second set, it does not mean that the first set was a waste and the second was magic, but that they added up.