If you say so. There is never a reason to have more than 4-6 trainees though. You cannot argue that. Even 4-6 is a huge stretch. Usually 3 is the max unless you are training multiple positions. None of your players are going to reach 1/4 of their potential with how many you are trying to develop. I also do not think that it is that hard to promote to D.III. Myself and many other managers have promoted to D.III after only a few seasons in D.IV. In fact if i remember correctly i think I went from D.V to D.III in two seasons without much trouble. I personally would not let you coach our U21NT but maybe in smaller countries they wont care as much.
Yeah, and you're not even that good of a manager! ;)
(closed captioning for the humor impaired: The preceding was a joke. EBW is a fine manager, a gentleman of impeccable quality and sterling reputation, and other adjectives that seem appropriate).
And definitely agreed on having a team full of young, high potential players. If you're not actively training a player, his potential is pointless, and if you're not going to cap them, then you don't need all of their potential anyhow. Non-training players should be purchased with an eye toward getting cost-effective players with good secondary skills for the lowest price/salary possible, and you're very unlikely to find that kind of deal with young, trainable players because you'll be competing in the market against people who want to train them properly.