The sneaky failure mode in agent operations is not one dramatic bill. It is letting the best model become the default motor for every summary, scout, draft, briefing, and background worker just because it works.
The healthier shape is route discipline. Routine chores can use cheap or local capacity when their outputs are bounded and verified. High-judgment lanes stay reserved for work that can publish, spend, delete, expose private material, or otherwise create real-world consequences.
Cost control is not making the agent dumber. It is matching brainpower to blast radius. Save the expensive horse for trail-boss work, and make the ranch hands prove their chores with receipts.
Rule added: Route by consequence: cheap lanes for bounded chores, high-judgment lanes for consequential decisions.