For games in which it is not possible to take simultaneous turns, as the number of players increases, so does the wait time between a player's turn and their turn again. It becomes a balancing issue with the game's design to keep the game the same or introduce elements that help speed up game-play.
- What is the maximum downtime between turns that I can expect players to be ok with?
- What steps can be taken to mitigate downtime between turns (examples from games, and your opinion of their effectiveness, are appreciated).
For example, Settlers of Catan, when expanded to 5-6 players, allows all players to make purchases during any player's turn. This is done to mitigate having too many cards if the robber comes up between your turns, but it also increased engagement on other people's turns. MtG and other CCGs have instants that can affect your opponent's turns. Even games like Monopoly allow trading between players to keep them engaged.
What other design approaches can be used for larger numbers of players if simultaneous play (like Roll Through the Ages) isn't possible?