The sizing heuristics:

• Managers should have 6-8 direct reports. Below 6, managers tend to micromanage or become overly involved in technical execution. Above 8, they become a communication bottleneck and lose the ability to provide meaningful mentorship.
• Managers-of-managers should have 4-6 managers. The coordination overhead per report is higher at this level because each conversation carries organizational implications.
• Teams should never be smaller than 4. Below 4, a team cannot sustain on-call rotations, absorb vacations, and maintain project work simultaneously. A 3-person team with one person on vacation and one on-call has zero people doing project work.
• The "two-pizza team" only works if it's actually staffed. Amazon's famous heuristic is about communication overhead, but a two-pizza team of 3 people is just understaffed.

Growth and shrinkage rules:

• When growing: add engineers to existing teams before creating new ones. New teams carry coordination overhead that established teams have already absorbed.
• When shrinking: merge teams rather than letting them dwindle below 4. A team of 2-3 is organizationally expensive relative to its output.

Sizing also affects information flow. Too many reports means the manager becomes a bottleneck for decisions, context, and conflict resolution. Too few means the manager has excess capacity that often manifests as micromanagement or unnecessary process creation.