Watch Timing Machine

[dannyf]

No point in adjusting a quartz with another quartz, you'll need something significantly better.

Plenty of cases where a quartz oscillator is calibrated via another quartz oscillator.

[wraper]

Quartz can be pretty precise, IIRC my Swatch irony diaphane quartz watch was out for about 1-2 seconds in a month. Don't use it for a few years now, would need to remove it from the hand few time a day because of my job.