When a homeowner asks for one more outlet, a different finish or another repair while the crew is already there, capture the change before anyone starts it. A written record protects the job handoff and gives the invoice a clear reference.
Caltrans’ contract-administration guidance says change orders should document the need for the change and include enough information to explain the changed scope. The same habit is useful on smaller residential jobs: write the request, approval and cost effect while the details are fresh.
Reference: Caltrans, Chapter 5, Section 3: Change Orders. This page is a workflow aid, not legal, tax or contract advice.