Before reaching for AI, walk the ladder: rule → router → template → calculator → validator → AI → AI agent → human. Each step up costs more and runs slower than the one below it, and from validator through agent each step is harder to predict and to audit. The human sits at the top not because people are unpredictable, but because someone must own the consequences.
Use the cheapest mechanism that is reliably correct; escalate only when the rung below demonstrably can’t do the job — and “demonstrably” means a failing test set, not a hunch. In my own products, most “AI features” turned out to be rules, templates, or calculators wearing a costume — and they got faster, cheaper, and more auditable the day I demoted them.