Everyone has a right to express their opinion. I am listening, just not agreeing. The substitution code is what it is for now, imperfect and yet still it somehow works for most teams. Remember, this game was never supposed to follow all of the players wishes, in that case, we can just add a textbox for each player in which you can just insert the wished number of minutes and be done with it. It's supposed to be challenging.
Also, since the game was not designed to have players play 48 minutes per game, expecting to get those minutes is unrealistic. It's a trade off, just like with everything - you risk not getting the full 48 minutes per game but gain the ability to train better players (faster - if it works). You could train 5 guys in two positions, and the risk of not getting full (weekly training) minutes is much smaller.