Ignoramus30509 wrote:

A week ago I posted a surprised message about a $6 watch from walmart
that seemed to be accurate.

I have a little more data now.

About 2 weeks ago, I set this watch very accurately to time that is
kept by syncronizing with an NTP server (atomic clock), to the second.

Today I checked time again whiel trying to be very good at catching
the right moment. I typed "date" and pressed ENTER just as the arm of
the watch passed :00:00.

The result is that the watch is not even by one second off!!!
Obviously, there are limits to my own precision in how I pressed the
return key right when the watch ticked :00, plus the OS delay in
starting "date", but in any case I could not detect any difference.

I find it rather amazing, really.

The watch is a quartz watch with hands, "water resistant".

Quartz crystal oscillators can be extremely precise. I worked in an electronics
design group for awhile that designed crystal oscillator chips, so I felt a pull
to own a watch which used one. I wound up with a nice Tag Heuer, keeps great
time too.

GWE