Mechanical watches can last a lifetime (or more) if properly maintained and periodically serviced, just like old cars.

People all over the world pass down their Rolexes and Omegas, still ticking, to their children and even grandchildren. Patek Philippe is well known for their slogan, "You never actually own a Patek Philippe. You merely look after it for the next generation," showing confidence in the longevity of their watches.

Of course those are very expensive brands, but I think part of what makes expensive watches last longer is that their owners take good care of them. Few people bother to get their SKX checked up on a regular schedule, on the other hand, because they're so cheap and easily replaceable by first-world standards.

They also cost a ton to service. It's nice if the sentiment of carrying something through the years appeals to you, but the thing that keeps me away from mechanical watches is the service costs compared to the odd battery replacement on a quartz.

My father's Seiko from the late 70s still keeps time at around 30 seconds per day. It has never been serviced so I am sure it is bone dry and really should not be run. I regularly wear a 2015 Seiko that used to be 8 seconds per day fast but has fallen to 5 seconds per day slow so it is probably time to service it. My two newest watches are from 2017 and 2021 and they are consistent since break in. So given my limited number of data points, I would say 5-7 years between service but if you just want to wear it until it dies, 10+ years is probably reasonable.

On a side note, I have read about 40 year old Seikos being worn daily without service but that sure feels outside of the norm.

I have a 7s26A movement out of a late 90s SKX which was unserviceable, and another 7s26C became unusable after 4-5 months of use.

I also have a replacement 7s26C which worked flawlessly [-5,+5] s/d out of the box and a year so far, and another watch with NH35 which still holds [-5,+5] s/d after seven years of daily use.

There are stories of SKX:s which hold good time after 20 years.

There are much cheaper watches than SKX (at their current prices) that will withstand the depth, see "Beyond on the press" pressure chamber tests, for example https://www.youtube.com/watch?v=Ti-GdfGbj4Y

I think maintenance requirements are overstated. I wore a relatively cheap (~£120) mechanical watch continuously for about 8 years, and never had a single problem with it. I only stopped wearing it about 2 years ago when I finally bought a smartwatch. It still works fine, I just don't wear it except on special occasions.

If your watch is a sizable investment then maybe you care about maintenance more, but otherwise I wouldn't worry that it's going to stop working in short order.

If you are going to take your SKX diving, you probably want to have a watchmaker pressure test it once in a while and make repairs as needed. The seals dry out and water will get in.

> Are there other automatics that will outlast a person’s life?

Very unlikely. You do hear the occasional story of a mechanical watch running fine for several decades without requiring any servicing, but there's a lot of survivorship bias at play there. It's extremely unlikely to go ~8 decades without needing servicing. Keep in mind there are lubricants at various places in the movement that are essential to proper operation that evaporate/denature over time.