Well in China the flights between Beijing and Shanghai, the two biggest cities, are mostly wide-body jets like 788, A332, even 748, 77W and the latest A350. And the frequency is basically half an hour a flight. And all the four major airlines in China (Air China, China Eastern, China Southern and Hainan) do that. And most of the flights are full, each with over 50 gold and platinum members on board.
Flights between Beijing and Guangzhou, Shenzhen are more or less the same.
Guess you offer your best to the cash cows. Interesting thing is, even with high speed railway that gave people more comfortable options (but not necessarily cheaper price), the flights are still crowded.
One of the reason is probably because there are not many regional flights in China. Chinese people travel from hub to hub much more often than the US.
I sometimes found these large jets fly international lines before their domestic flights. And at that time passengers will have to take shuttle bus from domestic departure to the international bridges where these jets were parked. Pain in the ass.