Accuracy of new watches: 117610LN, a watch that is several years old and hasn't been serviced since new: ~+1 sec per week. Seriously. That is either on my wrist or on the watch winder. Cartier Santos (a brand new watch): +1-3 sec per week. Again, seriously, with it either on my wrist (which has been a lot) or on the winder! New Speedmaster: I can't quite tell, as I need to set it each time I wear it (too many watches!), but it seems to be about... drumroll... +1-3 sec a week. Man, modern mechanical watches rock.