Obviously working long hours isn't necessarily optimal for productively, but the average Korean certainly works harder than the average human. (And I'd wager this extends to the North too.)
If you look at the post WWII economic performance of South Korea, and North Korea until ~1980 or so when their leadership started to impede them, it is clear the peninsula has what you might call very high levels of latent human capital, seeing as how just about all of their physical capital had been destroyed.
That's a real potential problem, as is the lifetime impairment of childhood malnutrition. But I expect defectors from any regime to be the kind of entrepreneurial misfits that never quite fit in and demand their environment adapt to them.
http://www.vagabondjourney.com/south-korean-work-hours-highe...
Obviously working long hours isn't necessarily optimal for productively, but the average Korean certainly works harder than the average human. (And I'd wager this extends to the North too.)