Well, when the collapse happens and you have no batteries, satellites, etc., you can use the stars[1] to tell time and reset your mechanical watch to within a reasonable estimate given the circumstances. I own a relatively cheap mechancal watch I adjust every week. I bought a Garmin vs. an Apple/Samsung watch too. My Garmin battery lasts about 20 to 24 days depending on how I use the watch vs. 24 to 48 hours. It does more than I need, but has come in handy in my line of work.

[1] https://www.timeanddate.com/astronomy/tell-time-by-stars.htm...