I used oxygen from camp 3 up. In total I used eight. I was on oxygen all that time. The way I summitted was the hard way, by spending 11 days and 10 nights at altitude. Five of those nights were in the death zone.
Most people try to get in and out in two days of two and a half.
It was a combination of things, I knew if I descended that I might not get back up. I knew the window was closing, with the weather prognosis and the number of climbers still trying to get up. It is very hard being up high. For my own, they acted as a distraction and created bigger problems than were probably there. The other climbers haven't spent a lot of time with reporters and don't understand their role.