Fast/slow trainers

[cookizzz]

There's a lot of talk about players who are fast or slow trainers, and clearly faster trainers are more beneficial than slower ones; but I'm wondering how fast a players growth can be?

Here's a print screen of my team after everyone did a normal intensity stretching training session. Obviously  dos Santos Moura is the clubs fastest trainer, and S El Quabbani is the slowest, and it's no surprise with those two considering the 12 year age gap, but C de Oliveira Costa is the youngest and he's a fairly slow trainer.

I think I heard somewhere that the players quality also affects their training speed, but again I'm not too sure how it works.

What's the highest growth you've seen of a player, and how do you think this could be improved?

Cheers!



Edit:
Side-note, ignore the horrible formation that I've currently set up; I've already won the league so I'm just playing the players with the least morale to boost it a bit

I haven't study how the fastest trainer can be. My current fastest trainer is 18 years old and gains +19.2 in average for normal sketching exercise. He should easily gain 100+ through high intensity practice match. Your  dos Santos Moura is just a slight above average trainer.

It's true that young players are generally faster in training but it is not difficult to find some 18 years old slow trainers. In low levels, you can easily notice them as their market price is significantly lower than other players at same age. There is no way to improve training efficiency of players. The efficiency will drop when a player move up to new star level. Fast trainers are not necessarily good players. They may quickly grow and poorly perform. Slow trainers can be good too.