Well, I don't really accept the LIMITATIONS of training sessions in FM. It's very weird as a manager to only have access to the players two days in a week, even if it's not a fully professional team. And also, currently you can't even choose the days yourself. You are limited to tuesdays and thursdays for some reason. That's perhaps the strangest and most arbitrary limitation in the game. Scheduling a friendly is doable though because that makes sense, or does it?
A reasonable limitation however, related to what you are bringing up, would be to just have 1 available session per day for teams where a significant part of the squad don't reach the 'Minimum acceptable full time salary for an adult'. Because that is realistic and makes sense.