Well, again, my 34-year old one owner Rolex Oyster Date-Just, in constant use since put back into service on March 11. Worn 24/7 since then, the time has varied over the past 35 days, from 3 seconds slow, to 2 seconds fast. This morning it is dead on! How much better performance might one expect out of any mechanical watch? I’m about to commence using this watch as a time standard to rate the (only) two quartz watches in my stable.