Keep teams small enough to be fed by two pizzas, because coordination cost is the binding constraint.
Bezos's rule at Amazon. It is Brooks's law applied at the design stage: keep the unit small enough that its internal communication cost stays below what it produces.
In practice
- A team of six ships weekly; the same team at fourteen ships fortnightly and spends the difference in stand-ups.
- A charity's organising group splits at twelve into two groups of six, and both deliver more than the twelve did.