I did three days once and was still lucid. Wasn’t even really tired, so I even went clubbing until 5am on the last night. I could have stayed up longer, but I had no reason to be up anymore, so I got four or five hours of sleep and was back on schedule. Some people just can’t do that kind of thing, and it seems to be easier for others. Dude from China sounds like a machine though. I’d guess be was the right combination of the kind of person who doesn’t require a lot of sleep and stubborn as hell.