[gardenfelder]

I wonder how Robin Dunbar [1] would weigh in on this question. He originally wrote that the largest stable social network was around 150 people - laying waste to people on MySpace claiming 1000+ friends. More recently, he co-authored a paper which says it' closer to half dozen. If you have a large group, you break it up into smaller "committees" - in World of Warcraft, guilds have role players. The WorldCafe [2] argues for 5.

In a recent "agile" project we formed a group of 5 people, 3 of which took on the software dev task and the result was fantastic.

[1] https://en.wikipedia.org/wiki/Robin_Dunbar

[2] http://theworldcafe.com/