Funny. I just read about 996 in a comment on another HN post today. I couldn't believe that schedule could actually exist in Chinese workplace culture so I started doing some research. Sure enough, this hellish schedule is actually quite common and official at major Chinese startups and tech companies. It seems like it's not as common at western companies operating in China. There's even a joke about 007: 0AM-0AM, 7 days a week.
Of course this flies in the face of my own experience that for the majority of people, productivity tops out at 40 hours per week unless it's for very short periods of crunch time. It's odd to see people so burnt out they've lost the self awareness to see that they've stopped adding value with their perpetual motion.