In the January issue of New Scientist, there is a article about Parkinson's Law and how researchers in Austria put the law in a more scientific footing via mathematic. The essence of the law is, "work expands to fill the time available for its completion", which is intriguing but I am more interested in the second half of the article where Parkinson's limit is discussed.
Parkinson conjectured that there is a limit to any working group/committee size (20) beyond which no consensus would be reached no matter how the group is structured. I am curious whether this is also the limit of an agile/XP team size since an agile team tends to be of a flatter structurally (verses the traditional hierarchical nature).
Parkinson also noted that there is an anomaly around group with 8 members. He noticed that, for example, no nation has cabinet of 8 members. I have the good(?) fortune of working with teams sized on either size of 8 so I can't verify this claim. I wonder what are the proportion of previous failed or not so successful projects had exactly 8 team members. Then the question of how would one define team members. Would only developers, testers, BA count as a team member and not PM because they work very closely together day-in and day-out, whereas PM less so?
If you have previously (or currently) worked with team of 8 or larger than 20, what is your experience? Does the group dynamic change when the group size hit 8 or grew larger than 20?