Power training

[Jetzki]

So it seems like my new striker D Jarecki trains amazingly well, should I be training the crap out of him before the new season starts?

Will his training slow down as he gets a year older? I want to push him up to at least 20 asap.

Also... any idea why my 21 year old ST E Laquidain only got 20 points from that training session?! He's so young, but trains so slowly, is it because he is 5*? That doesn't make sense to me since L Zhu got 148 and he is 4*