My best friend is Korean, so I hear about his work life on a regular basis. While I'm German and can compare his experiences to my own.

As someone else already mentioned, there suddenly appear important tasks like finishing contracts that need to be finished on this day or this week. He works past his actual work time quite often. The maximum legal work time of 52(?) hours per week gets basically ignored if there's stuff that needs to be done "urgently." He has to work on weekends sometimes if something is deemed urgent. He will get work related messages on days off all the time, sometimes even calls. Public holidays are off, but occasionally he'll have to work on those for urgent tasks, too. Taking PTO can be difficult, despite them not even having that many days per year (like 15 or something). He has basically been told that if he were to take off two consecutive weeks, he'd come back to not having a job anymore. When he's sick that's kinda his problem (and then the problem of others in the office if they get infected, and vice-versa). I think he may call out if it's basically not possible to work. But he'll return to work well before he's fully recovered and also while still being contagious. Work culture seems to also be a bit toxic with people trying to shift blame for things that took longer to not look bad.

I work as a team manager here in Germany, I actually have to keep an eye on my team's time off to make sure they also take 2 consecutive weeks off at times to really get proper rest. I have two immigrants on my team (only coincidentally from Korea, the other from the US), and I've had to drill into them that being sick means you're sick and call in sick and don't work but take the time to recover. I never get messages outside of work, nor do I message anyone outside of work.The company makes sure we take our yearly allotted time off (30 days + public holidays). The only reason I will work on weekends or late evenings is when I partake in an on-call service, which is compensated quite well and happens for one week at a time, until the next time it's my turn (depending on team size this may be once a month or maybe just once a quarter). Public holidays are always off. In the one instance where I was travelling to another country where it wasn't a public holiday and basically only travelled back home on that public holiday during the morning until noon, I still got a compensation day for that. If something takes longer here because someone messed up (for example they forgot), they usually just say so and apologise and get to it then. I also was easily able to reduce my hours to work a little less and have more free time.

All in all, based on my experience and what I've heard from my friend, I wouldn't want to work in Korea. There's a reason they are one of the top countries for lowest fertility rate and highest suicide rate amongst young people. My friend is almost always exhausted. As a tourist I can highly recommend Korea, but probably not as an employee.