Mythical Man-Month

Fred Brooks's insight that adding people to a late software project makes it later. Communication overhead grows quadratically with team size (n people require n(n-1)/2 communication channels), while productive capacity grows only linearly. A task that takes one person ten months cannot be done by ten people in one month because the coordination cost overwhelms the additional capacity. The deeper insight: some work is partitionable (can be divided) and some isn't. Pregnancy takes nine months regardless of how many people you assign.

When to use it

When a project is behind schedule and the instinct is to add people; when team size is growing but output isn't scaling proportionally; when meeting load is consuming productive hours; when deciding between one large team and multiple small teams.

How it can help

Before adding headcount to a delayed project, ask: is the bottleneck capacity or coordination? If the team is already spending significant time in meetings, handoffs, and alignment, adding people increases coordination costs without proportional output gains. The counter-intuitive solution is often subtracting: smaller, more focused teams with fewer communication channels frequently outperform larger teams. Apply this to any knowledge work, not just software.