do you know if the 10 seconds assumes continuous use with watch winder when not being worn?
The short answer is NO. The Swiss-based COSC organization, which is the largest that grants chronometer certificates, describes their tests as snapshots of performance at the time of testing and not a guarantee of future accuracy. Completely understandable as the manufacturers, which case-up the movements after testing, and end-user owners control a multitude of variables which affect accuracy. FWIW, watch winders are generally not recommended by service technicians who say they often accelerate wear and tear on the movement. These same technicians agree that the #1 cause for loss of accuracy of a mechanical movement is magnetism acquired from proximity to electronic devices, #2 being lack of regular service to clean and lubricate these complicated mechanical machines.
COSC has an entirely automated process that tests thousands of movements at a time over fifteen days. In 2020 they completed 1.8 million tests! The movements are automatically wound at the same time every day and, among other specifications dealing with positions and temperatures, if their daily average rate falls between 4 seconds slow and 6 seconds fast they are granted a certificate and returned to the manufacturer to put into a case.
There has been an explosion in the past few decades of other agencies that also test and issue chronometer certification. Some watch manufacturers have created their own in-house testing, others like Omega have added an additional level of testing to their COSC movements. Regardless of the process, they are all quite similar with tolerances of around 5 or 6 seconds per day.
Knowing the really amazing results obtained from mechanical navigation chronometers, I view these modern chronometer tests to be mostly marketing strategies. There was an elite sub-set of chronometer watches in the pre-quartz era that were tested over
3 months by astronomical Observatories which competed for prizes as the most accurate watches in the world. These numbered in the hundreds, not millions