don7t take advice from guys also in DIV that have never made higher divisions. If you want to know about training, talk to NT coaches and U21 coaches and guys who've promoted while training and made profits/usuable players with their trainees. more bad advice than good on these forums most of the time.
Wow, I can't believe it's this time of the year again! ;)
You clearly have a definition of "usable" that is perfectly relevant to your situation but does not at all apply to the USA. I still am playing two of the star guys that I trained from my first full season here as my starting and backup PG, in what is inarguably one of if not the toughest III series in the USA, and they're getting ready for the playoffs. Now, they're not at all elite or even particularly good fits for my current offense, and the one that is a backup is one of the next few players to be replaced, but the "unusable" players still played a big role in getting me out of V, then out of IV, and holding down a place in III while I've worked on training higher potential guys.
Personally, I'm surprised you'd mention listening to NT/U21 coaches as a reference - of course they understand training but the last thing a new team needs to do is building those types of players. If anything, teams at the lowest levels who do choose to train higher potential guys should work on getting their secondary skills up while at the lowest levels rather than, say, spending four seasons in III doing so. ;)