that would only save $15K per week and seriously destory your teams developement. hardly worth it for stunting your teams players growth.

And more important: Keep your talents or sell them for good money!

and keep them at 100% energy. over training achieves nothing

the thing about having as few players is you will start working on your depth chart later than others.

On the other hand you might be able to train them more efficiently since you can afford coaches sooner but the difference between 18 and 30 players should probably be less than 24000 per week. The difference between training with full coaches(20) and training facilities(20) is 40 points(if memory serves me right).
If you find the players for the 18 most effective positions in GI you should on most gamedays do better than anyone starting at the same time as you. You ll have to remember which bpos will go up if you were to play a player at 2 positions.
On the flip side, most managers are worried that injuries at key positions will hit you harder, if you donot have more depth at key positions soon enough.

If I were to start over, I'd just start with the minimum 17 (qb wr/te mlb sf 2*cb de dl 2*olb ol*3 rb 2*wr/te +defenders/OL/K-P ) but I like what to most ppl looks like long odds- so not too many "veterans" would probably agree with me.