South Korea has some of the highest rates of suicide, absolutely no government oversight that isn't corrupt, is an insanely nepotistic country in regards to jobs, have practically zero workers benefits or protections, the pay is abysmal, and they already work some of the longest hours in the developed world.
The country would simply cease to exist with a mandatory standard 69 hour work week. The birthrate alone would almost instantly plummet to a little over zero.