How much "better" is it to have a specific role - training?

So.. I holiday:ed (or whatever it is called) a season on a new FM save & I forgot to select training methods (like, specific roles/attribute) so all the player went one season with "default" training methods,
how much does this affect the players/player attributes?

So.. "TL;DR": No specific training (leaving it be) vs Specific training (Specific role/attribute), how huge is the difference in attributes?

(Sorry if this is hard to read, but i'm pretty tired.. hope i make sense..)