It takes 40 hours to get from Zhengzhou to Tibet. In this case, one day will be wasted. How long do you travelers usually stay in Tibet for self-guided tours?

Zhengzhou to Tibet departs in the early morning and arrives the next night. It takes 4 days to go back and forth.

Only for the time in Tibet, 15-20 days is appropriate. Slightly worse, 10 days. As mentioned above, it is not easy to come here, so take as long as possible, but in fact 15-20 days is not enough. Tibet is indeed not a place that you can travel to in one trip. 15-20 days is just enough time to travel to Tibet. You can take more of the best travel routes.

Oxygen bottles are basically not needed. Occasionally, you can prepare a small tank of oxygen or an oxygen bag when going to high altitude areas, just in case. Just buy this when you get to Lhasa.