Players train like they are proggrammed to train by default.
Youngers of 18 to 22 are the faster trainers, and academy players of 4* , and Nordgens obtained from Bot teams when the new nordeus days start, are very, very very good trainers and players (I've 2 now)

Too my form to compare players to see if train fast, in the market, is to see the Value, and Wage of the player.
If Value is x20, (in level 12) times the wage = good trainer, because the training increases the value, but not the wage.
In level 1... the differance is higher, coz are salaries of 5k and values of 1Million... so, that's to compare players between the level 1 to near 20.
In the level 20 or near, and levels under (21,22,55....) players have a max. of value, because this game have a maxium of Budget of 2.43Billions, so... the max. value is 110M or so.... and if the Value is not increased with training you can not compare with my method.

Too go to the group link of my signature if u want to be the member 60 of the O.M.A.