Youth academy players?

[Toxcatl]

Yep, instant win! Will try your suggestions. Have been throwing multiple trainings sets out there to see what works best

You won't see what works best, it's impossible. There is no criteria to do so, especially after just a few training sessions -- the difference will be slim to nothing. Drills of the same level improve the player's quality at the same rate, by the way.
To make a difference, you have to train players for a season, más o menos, with the same training routine again and again, and maybe after that you will have a feeling that you are doing something right. Or not.
That feeling most likely will be wrong anyway xD There are too many additional unknown factors in this game. It is a question of believing, not knowing. Welcome to Top Eleven.