“Human in the loop” often means one of two bad designs: a person approves everything, or a person appears only after something goes seriously wrong.
The better question is where human judgment changes the outcome enough to justify its cost.
Put People at Irreversible Boundaries
Human approval is most valuable before consequential actions: spending money, deleting data, sending public communication, changing legal or medical records, or making decisions with weak evidence.
Low-risk, reversible work can usually run automatically with monitoring and sampling.
Use Humans to Calibrate the System
People should label representative examples, resolve ambiguous evaluation cases, review judge disagreements, and define product rubrics. This improves automation rather than creating a permanent review bottleneck.
Route cases to humans using risk and uncertainty. A high-value transaction with conflicting evidence deserves review. A routine classification with strong deterministic validation probably does not.
Make Review Actionable
A reviewer needs the input, model output, retrieved evidence, tool history, policy, and a clear decision. Asking someone to judge an isolated answer recreates the same missing context that caused the problem.
Record the decision and reason. Valuable reviews should become evaluation cases, policy updates, or workflow improvements.
Humans belong where context, responsibility, and consequences are highest. Automation should remove repetitive work while preserving deliberate control over decisions the organization must be able to explain.