I had him pop in JS when he was 20 then I gave him 2 trainings JS, 6 IS and 3 1on1, the pop before took 1 JS, 1 JR and 3 1on1 I thought that was a steep increase but it might be the year difference. He also had 6 trainings in RB without a pop, but 3 of them was not ful minutes (the pop before was 3 trainings for one pop). So the data is not good but to me it looks like its somewhat slowed.
Let me see if I understand. After his last jump shot pop, you gave him 2 weeks jump shot, 6 weeks of inside shot then 3 weeks 1 on 1 training at 20 and did not get a pop? If so, it is pretty safe to say he was capped. I would not expect that much of a decrease in training from 19 to 20. Even if you mean he was 21, that is really slow training.
If this is what you are saying, I think it is pretty safe for me to use his data.
Run of the Mill Canadian Manager