by Sarimrune
As other’s have said, the primary factor is downtime.This isn’t what I would call a high co-op game. You don’t do anything on other player’s turn but watch. So in a 5 player game, depending on how long it takes to come to decisions, you could be sitting around for 10-20 minutes between turns. 20 is the outside I’ve had to wait between my turns, but it has happened. 5 minutes to complete each player’s turn is not unreasonably, but many (experienced) players can complete their turns in under 5 mins, especially when the choices become more obvious (such as the endgame boss fight).
Generally speaking, I often avoid this game at 5 players unless I know that the players need a more straightforward game. I weigh the level of engagement vs straightforwardness of the rules. I found the sweet spot to be 3 to 4 players, at least for many of my groups.