I have to say that remaining 3.5-4 hours are spent on other tasks like documentation reviews, etc.

For time being we can assume relationship of performance regression is 4/ToT if ToT more than 4. This means that these Chinese workers perform 3.5 less work per hour or even less so. One can try to compensate by hiring more workers, say, 3.5 more workers but then the amount of communication will increase quadratically and there will be more than 12 times increase in communication needed for team(s) to work.

That means that "996" policy results in great underutilization of people's potential. My napkin calculation is that each "996" worker performs less than 1/30 of what he/she can do.

Regardless of culture, it is sad.