Computer clocks are no more accurate than their master clock (crystal)
frequency. This is one reason to update via the Internet perhaps once or twice
a month.

For what it is worth, the radios I work on have their master clock set to better
(far better) than 1 part per million. Those clocks would be quite accurate –
except that they also sync to the gps satellites. Now you’re talking
accuracies somewhere near atomic clocks. Since the devices do have gps,
consider if they were off only 1/10 of a second. How far would the earth turn
in that brief time? Enough to show you on the wrong street, I’d almost
guarantee.

Just set the computer clock once in a while over the Internet, relax, and enjoy.