How large should communities be

So today's question is:
How large should the communities be? (max size before fragmentation ~150, but smaller communities are way stickier) Guilds (huge), parties (dozen max? complimentary careers encourage party formation), clans, secret societies, town councils... (intermediate size, for faction vs faction combat). There are advantages of both large and small communities - encourage both, in as many forms as possible to increase player stickiness. Avoid capping community sizes.


This can be a difficult thing to determine.  I am hoping that by having the various echelons that people will be able to be a part of smaller groups while at the same time being part of a larger organizations.  I think that names will first be a part of the platoon sized elements, so it could be something like Dragon company Vigilance Platoon.  I know how important names are to the various groups found in MMO because names often follows individuals and groups from game to game.  Because of the way military is set up one simply needs to expand and elect leadership to whatever echelon size is needed.