People have had time to get a squad together. If club's haven't reached it yet then that's their problem for being useless. Clubs can sign however many players they want. Clubs and players to remember that there are not due to have their own reserve teams, so having a mass of players is pointless. So really having more than about 21 is fairly pointless.
So having less than 21 players means you're useless, but having more than 21 players is pointless and means you've wasted time. SoccerSim is a fine art guys!
Just to clarify to sides that my suggestion of not going above 21 is no longer relevant after reserves sides were brought back in.