Answer: define pass criteria before the order, and keep the trial small enough that failing it is affordable.
- Write the pass criteria — functional test at target resolution/rate, E-Marker read-out, length tolerance, jacket print.
- Test the whole lot, not one piece — a trial exists to find the defect rate.
- Keep sample and mass production on the same line — ask which line the trial ran on, and whether mass production stays there.
- Agree the scale-up condition in advance — what result triggers the larger order.
A trial without pass criteria is just a small order you cannot judge.