Sometimes the people waiting for the big room to finish are already enough to start a new game. I don't know if they really want to wait or they only fear that nobody will join a potential new room.
I think some force should be applied to split rooms better. Does the !split command even still exist? I think a votesplit could be casted automatically if there are more than 12 players in a room, but only if parallelized votes are made possible so that other votes can happen at the same time. Some vote commands could be parallelized to reduce voting delays.
And I think it should be possible to enter a minimum team size for which you are available in the teams matchmaker because currently, it's only a 2v2 matchmaker.