Are quartz watches more correct than mechanical ones?
In general that’s right, but not always. Precision and accuracy is not the same thing indeed.
It is of great importance to keep in mind that even if a mechanical watch is permitted to vary +6/-4 seconds per day, it doesn’t mean that it will permanently vary by that high amount every day. Mechanical motions – but very scarce ‘turbillon’ motions – are significantly influenced by the gravitational force of the Earth. It only concerns performance deformation of 1/1000th of a percent for watch motion to be one second less precise in a day. It give rise to the performance of mechanical motions to be a bit diverse from day to day when it is not fixed in a stable position. The good thing is that factual changes of a mechanical watch will always balance with each other. It means that mechanical watches are more precise during a long time than the single day the COSC measuring might mean.
The everyday performance of quartz is more coordinated than mechanical under the same conditions. Quartz performance is influenced specifically by changes of temperature and underdesigned batteries. So a quartz watch that took 0.5 seconds yesterday will be permanently off the right time by about that amount. You can be sure that in two months it will be about 30 seconds off. At the end of the year, it is very likely to be over 180 seconds off.
Draw an analogy between this and a mechanical watch that you defined to gain 2 seconds yesterday. It would appear that our illustration quartz watch is 4 times more precise that this. But while quotidian measured quotidian changes appear much higher, they are hardly to be as uncontroversial, so will have a retarding effect. You cannot precisely denounce that this mechanical would consequently be off by 120 seconds at the end of the same two months. It might be correct on time, or it can be 200 seconds off. That wider diapason of changes permits lots of mechanical watches to be more contiguous to correct time than the daily variation rate means. In a year some mechanical watches can be closer to the right time without...