Position Training -> does this effect the development of a player?

I like to retrain players to a position that could fit my tactics, or when i think a player could be suited for that position. Hiddink style

But when I do this to youngsters, will it effect their development as a player? Because they waste to much time with position training instead of normal training?

Yes, is the short answer.

Each position has a set of 'free attributes' which can develop with little cost to the player. The more positions, the fewer attributes are free. Generally a player with many positions will not have the best attributes when compared with a player who has kept to 1 or 2 positions, all else being equal.

Yes, is the short answer.

Each position has a set of 'free attributes' which can develop with little cost to the player. The more positions, the fewer attributes are free. Generally a player with many positions will not have the best attributes when compared with a player who has kept to 1 or 2 positions, all else being equal.

and what about if i have a rising star player an AML and i want him to know the AMR position as well will he suffer greatly from this ?

yes not greatly but his mental stats esp will not increase as much.

and what about if i have a rising star player an AML and i want him to know the AMR position as well will he suffer greatly from this ?

In a way. As training on the opposite side improves a players weaker foot (unless you have a rare, right footed left winger) and as a players weaker foot is improved, more attribute points are taken away from normal abilities.

For me i only train positions or ask players to learn PPM when their CA is closed to PA

otherwise i would have to tune down training workload a bit and that affects CA development slightly, in my opinion