Should I always choose individual role training or leave on default playing position?

[spiritdonkey]

Thoughts from this unanswered topic 

Let's say that my player is "natural" or "accomplished" in certain position and his role familiarity is about full green (Bradley Dack from Blackburn is natural on AMC and almost full green on Attacking Midfielder). 

Is there any reason to choose individual training - role - Attacking Midfielder in AMC and raise his workload? And if I stay him train on "AMC - default playing position" (without raising workload) will he develop effectively? 

Or is this "train specific role" feature just for players with bad role or position familiarity?