The attached link below on how to get off airplane quickly is standard practice on Chinese airplanes. This is one of the reasons I recommend anyone going to China to take a Chinese airline which will be your first introduction to the culture, I love it. They are experts on how to get off airplanes quickly and I used the same methods as them and it is pretty much the same as this article. I have been on Chinese airplanes when passengers are trying to get their items from the overhead bins before the airplane actually landed. They like to depart the airplane quickly and they know were all their items are stored. Also they will squeeze through the aisle way to get ahead and if you give them an inch they will take it. I wish all US airline passengers were as aggressive to de-board an airplane as the Chinese.
I was recently on a Delta flight and it took so long to de-board the plane I actually said to myself if we were in China the plane would already be empty from a large aircraft like the Boeing 777.
Worth noting, always arrive early for departures especially when flying inside China because their planes may leave early than scheduled.
As for immigration all I will say is most countries it is a breeze to get through immigration but in the United States as a US citizen it is a long long process. Much improvement needed.
Passionate for everything related to China travel.