Perhaps thoug hyou have made some progress and can show how players you trained gained greatly in value such that they were purchased by successful teams, considered for NTs and won you championships. If not thoug hI think its still just a theory taht training star potential is wothwile. It only takes a few minutes gandering at the TL and staff market to see that its unlikely most star trainees are worth teh cost of a trainer even if you cap them.
Roberto Tuozzi Bought Mario Boni numero 1 3/9/2011 $ 10 000
Roberto Tuozzi Sold Voreia Asteria 3/17/2012 $ 450 000
Now, of course, I had to pay his salary for one year, but as he was being trained for most of that year, I was getting performance out of him that was greater than his salary. And with the proceeds of the sale, I purchased a trainee that is more in line with the progression I intend to make over the next year or so (superstar potential). Of course, I was also training four other similar guys at the time (though, one was a one-season $1k to $75k jump, and was later replaced with an allstar).
And as I had to clarify probably before in the other thread and again to GM-Jason here, I am not at all saying that this is the best way for new players to train. I am simply stating that people are way too quick to write it off as entirely worthless. Despite the popular opinion, it is entirely possible to have a long-term plan that actually consists of multiple stages of development, rather than trying to start at the bottom and from the very beginning training three guys that would be useful to you when you get to the top levels of the game.
I suppose by your definition above, of course, I'm not successful, since my trainees aren't considered for NT or U21 play and I've not really won "championships" (I am assuming you mean top level here, not just V and IV). Luckily for me, my plan doesn't begin and end with star potential players - but I am very satisfied with where I am in the game given how long I've been here, and very satisfied indeed that now I am in a position to train higher potential players (out of position, no less!) and maintain where I am while I start to build the big men I will need to progress further, rather than the three-skill donkeys that litter the transfer list. I'm quite pleased to have done this with below average salaries, merchandise usually 50% above league average, and fairly heavy investment in my arena. If I've wasted these four seasons, so be it. ;)
but you could be working on the 19~21 y/os at that level, with higher potential and moving them along the process. If you promote to pay teh higher salary then you can keep them, or just make sure to train secondaries first, and blow up the salary last thing. wiht higher potential is relevant and valuable players.
Actually started with 18yo this year, as the plan called for me to almost cap the guards and then work in my future big men for training in guard positions for 1-2 seasons (and occasionally providing training to the guards via 1v1 or two positioning passing, heresy though that is). Unfortunately my draftee had some pretty poor outside skills other than OD, so it's looking more like two seasons of guard training than one, but I'm holding on pretty comfortably now so I imagine I'll survive.