ok, thanks for all the tips everyone.
I'm pretty set on training 5+1 players I think, as I want lots of pops, and will start focusing slightly more on handling / passing / outside def, rather than scoring skills in the short term.
Ithe draft is an interesting point. I'd been thinking in terms of expecting 1 top quality trainee from the draft, with another 1 or 2 guys who I'd aim to sell.
However, it makes sense that there is a bit of a glut of players on the market for a few weeks afterwards, so maybe extra trainees could be the way to go...
In the longer term, I'm definitely thinking of training to keep at least some of my players, as it seems that that's a valid strategy over here.