RE: [Demo notebook] QC clinic: photographic evidence and its limits · RWI-24597

Case 3 — Accuracy expectations: is -8 s/d acceptable on an entry-level automatic?

Start with how you measured it. Comparing against a phone clock once a day for a week, at the same time, and noting the offset is reliable enough. One 24-hour reading isn't, because rate depends on wrist time, position overnight and state of wind. Average across several days before deciding anything.