Gymwasp's agentic code review factory, called The Mandible, processed 372 issues over 6 months with 65% merge-ready after one review round and a cumulative pass rate of 87%. Analysis of 12,000 review rounds across seven parallel reviewer lanes shows diminishing returns after round 2, with oscillation rather than convergence, and reveals that naive averaging understates true cost by 44% when including issues shipped with warnings.