Anyone (including ANTHROP\C) "recommending selective use of cheaper models" is spending costly human time (which costs more over time) on correcting the machine (which costs less over time). This is a bad trade.
In cost per line of code, we have verified this is always an error unless your time is worth less than the machine (unlikely unless you consider your time to have no cost rather than considering it as your hourly rate).
The worst thing for our productivity has been Claude Code or Claude Cowork taking a complex problem and turning around and writing bad instructions for dumb model agents then synthesizing the dumb answers into an orchestra of badness.
The single best fix for results-per-total-cost is to ensure it reads and thinks about whole content, not snippets, and thinks with the smartest model, not agents.
Agents should toil. Agents should neither think*, nor decide what to think about which itself is thinking.
* Agents should “think” like ants or bees or beavers think. Any human-like thinking, *especially* intuition-like thinking, should be thought by the best model available.
** Nobody should be “churning out code”. In a hierarchy of coders who translate detailed specs to some computer language, developers who write software that ships on a project timeline, and engineers who accomplish business goals, engineers should “churn out” engines structured for business outcomes.
Measured by that, the machine is leverage while reducing a variety of costs. At the same time, because most training data doesn't grok this, the machine doesn't grok it either. So it needs you to shape its toil.