I just quickly skimmed this short thread(im lazy) and im assuming your talking about training a starting 5 of SFs?
You could grab three, One position train them until their skills that require one position training are at the point that you want them. Then you get 2 more trainees(or even 3) and you do all the two position training together. Afterwards you one position train the newer trainees. Youll end up with 3 players much older than the other 3, but they would still be useful into age 34 or 35 since a balanced skillset drops skills slower.
Its possible, however unlikely :)