OmniscientOnus
Blue Mage
I think it all depends on how the game revolves around the characters.
6 works in a game that partially develops everyone's back story no matter who you use, and fully develops the ones you use often. In other words, even if you choose to only use 3 (or 4 depending on what the game allows at a time) you still get at least most of the storyline behind everyone. Then, at certain points, whoever you had in your party at the time would have only their background(s) fully revealed.
More than 6 would work well in a game that only develops a character's background when they are in your party during certain points. The more the merrier in that scenario. Then the game (if it was good in the first place) has that much more replay value.
Less than 6 (I prefer 4) works in a game where everyone has their background fully developed no matter who is in your party.
6 works in a game that partially develops everyone's back story no matter who you use, and fully develops the ones you use often. In other words, even if you choose to only use 3 (or 4 depending on what the game allows at a time) you still get at least most of the storyline behind everyone. Then, at certain points, whoever you had in your party at the time would have only their background(s) fully revealed.
More than 6 would work well in a game that only develops a character's background when they are in your party during certain points. The more the merrier in that scenario. Then the game (if it was good in the first place) has that much more replay value.
Less than 6 (I prefer 4) works in a game where everyone has their background fully developed no matter who is in your party.