I think signing the academy players is really a matter of personal choice. As I keep a full squad of 22 players, signing one of the youngsters would require me selling one of my established players, so I rarely do it, and just let them go. Having said that, I did get a young striker back in level 4, that impressed me. I was lucky that it happened at the end of the season and I had a player that was about to retire. So I signed the newbie into the vacant place. He was a fast trainer and quickly made it up to 6* plus he learned two new positions. He stayed for 6 seasons and I eventually sold him for 72 million, (his value was 28m), because three bidders got into a bidding war over him.