However, ST are by nature usually fast trainers.... they cant be compared to Midfielders...
position has nothing to do with fast trainers.

the rule of value/wage was my rule and is not a rule LOL
yes, it's an indicator to recognize, it's not the reason why they are fast trainers.

Not true... I have a flop player in my team with higher value/wage number than fast trainer who got promoted with him from YA...

Flop Varela... 2.91M / 92K = 31.63
Fast trainer Semedo... 7.6M / 270K = 28.14
that's true, because you must compare players with same quality lv f.e. 1st class nordgens have low V/W, specially after lv4, but they are (99%) the faster trainers. 1st class nodgen has 7.6M/270K, 2nd class has 5.1M/240K 3rd class 3.9/250K.
Academy players (yours or from other team) are lottery. Usually 21T are fast trainers.