"two-pizza team": If you can't feed a team with two pizzas, it's too large. That limits a task force to five to seven people, depending on their appetites.
My new agile mentor Mike Cohn explains why this works:
- There is less social loafing
Psychologist Max Ringelmann coined the concept of Social Loafing, aka the Ringelmann Effect, in 1913.
[wikipedia on Ringelmann Effect] "...the lack of simultaneity of effort in groups, which interferes with efficiently combining individual inputs."
In other words - this concept explains the tendency that individuals have in larger groups to exert less effort because they believe that the mass will overcompensate for their minimal exertion.
- Constructive interaction is more likely to occur on a small team
Mike cites Stephen Robbins here:
[Stephen] has concluded that teams of more than 10 to 13 people have a difficult time establishing feelings of trust, mutual accountability, and cohesiveness. Without these, constructive interaction is difficult (2005, Essentials of Organizational Behavior)
- Less time is spent coordinating effort
This is a no-brainer... More bodies = More logistics. Trying to herd 10 people is exponentially more challenging than half that.
- No one can fade into the background
Yes, yes, and Yes. I don't know if you believe that humans are innately evil or good... but I believe that they're innately lazy. Let me ask you a question. What would you do with $1,000,000.00 lotto winning? Most folks that have taken my informal poll answer something to the effect of... "move to an island." God love them but most humans are lazy or at least exhibit laziness when given the chance.
- Small teams are more satisfying to their members
I concur. You get to feel like you're moving the needle. When you're just one of many, the joy and accolades of your accomplishments can get lost in the clutter.
- Harmful over-specialization is less likely to occur
I'm a fan of the generalist. Why not know as much as you can about numerous subjects?