I believe that the progress of a player in training is mainly influenced by his match performances and ratings. For example, managing Steaua in Romanian league, I had a Colombian ST, with 18 determination rated as realist. In one season he scored 40 goals in all competitions and had an overall rating of 7.70. He progressed extremely well and at a fast/constant pace.
On the other hand, at Newcastle (with better training facilities) I have a young French ST, 20 determination, rated as perfectionist. With the same training schedule, and with an average rating of 6.70, in half a season he didn’t progress at all, maybe an increase in one or 2 attributes.
So I would say that individual performances on the field + morale are the main factors to boost training productivity. just my 2 cents