squaresinger's point matches what I've found. Once three agents are going, you become the coordination point - you're holding the plan and reviewing all of it, and that part doesn't scale the way the generating does. What's kept it manageable for me is treating each one like an intern on a single, well-specified task I can check before it moves on, rather than running a swarm and hoping it converges. Wrote this up here: https://prickles.org/tenet/the-intern-pattern/AI1