ST, AM* and M* are Attack players.
GK, D* and DM* are Defence players.
At the same time, DM*, M* and AM* are Midfield players.
If you know this it's not that hard to train all bonuses with just 8 players.
This is my bench + reserve. There're 5 atk player and 4 def, and 7 midfielders. Enough to get all bonuses. After this seasons changes (I made a few mistakes) it requires a little more condition to go from 8% to 10%, something like 15-17% Condition loss with 2x videos. The exact rules how bonuses depend on positions and drills are still mystery for me, but I got some interesting facts about it. As I said, it's both art and science.
If you don't have enough players to train bonuses, you can always buy some cheap old guys to do just that. Youngsters from the Academy are great help too.