If you have enough people in the game, if the map is small, the play relatively simple, it can work to play many games. As long as people take their turns in a semi-disbursed fashion, you are fine. The problem is when one player maybe takes a bit less, another a bit longer and before long you have 10 games all "up" at once.
Then you suddenly wind up missing turns. This is utterly unreasonable for all the other players playing. I would not want to see an increase. If it is, it should ONLY be allowed for 6 player and up games.