It's easy enough to mistune a 32768Hz clock crystal by shitty electronics engineering, unfortunately :/
50Hz might have temporary variations, but it's controlled so that over a longer period of time, you always get the correct number of cycles, e.g. 180000 in an hour.
This also means that going off the 50Hz power grid theoretically has better (or even perfect) long-term accuracy. Also means that if you adjusted your clock for this separation event, you'll have to adjust it back :D
50Hz might have temporary variations, but it's controlled so that over a longer period of time, you always get the correct number of cycles, e.g. 180000 in an hour.
This also means that going off the 50Hz power grid theoretically has better (or even perfect) long-term accuracy. Also means that if you adjusted your clock for this separation event, you'll have to adjust it back :D