[Yodel0914]

> A well serviced rolex in 2026 with laser cut gears drifts +/- 15sec per day.

Modern Rolex (and Omega et al) are more like +/-2s.

[fainpul]

You would probably use a chronometer:

"The precision of a COSC-certified chronometer must be between -4 and +6 seconds per day."

https://www.cosc.swiss/cosc-faq