this will change by the time, the game will get older and more exciting - I don't think that the team can do league, cup and B3 by 5 players.. and if you decide to play B3, you will put there always your best I think because of the benefits (at least I would)
I pretty sure that there will ever differents, and if you aren't a total dominating player in your country, you had no extra team for B3 and to buy this need some time.
And i think even if the game is progressing, teams would have some stars not a lot average players, becuase i don't need the top players to win in the cup and a bit more quality in league could be pretty usefull.
In Cup there eare always promising teams from low devisin, who look that they got 8 strong players for a cup, and play with an weaker team in league and they don't get the money for so much good players but through focusssing they are pretty strong in cup and after it in their playOffs.
edit: I don't agree with "not" training players during a B3 game, isn't necessary to erase this benefit/difficulty
Yeah thats an point where we could discuss :)
Some people say splitting the team is a major mission and an important tactical choiche, i and some other wnat to play the strongest teams in B3, which plays the tactic where the manager ist mostly convinced of his succes and not which will fit best in their game plan(i got some players for outside and inside tactics)