Module 7 of 8
User testing
Watch someone else use it.
Sit with a person who does this work and watch them run the process without helping. Do not explain, do not correct, and write down every place they hesitate. Hesitation is data: it marks the points where your design and their mental model disagree.
Expect to find that something obvious to you is invisible to them — a status that is not shown, a notification that goes to the wrong person, a queue nobody told them to check. These are cheap to fix now and expensive to discover in month three.
Takeaway
Watch, do not help. Every hesitation marks a place the design and the user disagree.