BTW here is my original trainee that I drafted my first season: 18 Per All
7 7
4 2
4 6
7 7
5 6
Now at 21:
9 7
7 7
9 7
9 9
6 7
+1 stamina 3 EXP
In total 22 Pops. But I was a bit clueless and trained him in things like PG Handling and such early.
So most of his pops have come from driving/handling. By the time your player is 21 I am guessing he will have around 90 skill points. Something like:
10 6
10 12
14 8
9 9
8 8
I wouldn't cut short one on one training, but you may want to stop at 13 driving in order to get more ID/OD pops in. Either way I think he has a good shot to get on the U21 as a multi-purpose PG/SG/SF type probably coming off the bench filling multiple roles.