NT coaches are so worried about OD in young ages! Or why shouldn't we start buying players with low levels of OD but pretty good already in other skills and just train pressure.
Thats because sometimes NT's managers we go crazy haha ¡
Anyway, as i said before from my experience and opinion the best way to train a PG is to do it in a balanced way. Of course that if he has the OD in 6 or so you can train it to 9-10 or 11 fast but arrived to that point, its better to focus on his others skills.
You talk about maxiimize the player skill then you are wrong. If that player can defend well with a 11-12 OD, why you wanna go to OD 15 so fast? You can improve on passing and shooting and you will maximize his performance on the court and for the team performance it will be also better.
Anyway its true that doing what you said, you can have a rookie of 19 years playing on the court, but doing it on a balanced training you can have it with 20 and his performance will be better, not to talk that with 21 he can start to be a monster.
Just to conclude if you look at PG's performance of u21 teams you will see that the best PG's at this moment are not those who have a high OD and passing(so a monoskilled PG), the best are those who can defend, assist, shoot and drive under the basket.