Whouah how can I miss this thread ?

If I knew, we could have discussed about this when we met : we took the expressways twice during our round-China trip : once in Sichuan between Emeishan and Chengdu (the fools had opened the gate on the far right without anyone guarding it, and I was trying to get on this day, just to check how it was : lucky !), and the second time in Qinghai, as they forgot to put a gate when a national road became an expressway.
Both times we were "yelled at" when coming out of the expressway, but who cares... They didn't even want to open the gate for us to get off the expressway, but you just have to wait until a car comes...

The 1st one near Chengdu, we rode on it for 80km, with an average speed of 100 km/h. The second time in Qinghai, for 30km with an average speed of 110.

And with this little experience, my opinion is that :
- if by taking the expressway you're trying to avoid a very bad portion of road (mud, stones, dirt, etc.), then it's worth it to try.
- if not, you'd much better stay on the national and provincial roads : expressway are terribly annoying, it's flat, straight, you cannot see the landscape, it's just mafan...

The fun is on the small roads, even though yes it's dangerous with all the cars, ebikes, dogs, sheeps, etc. . But your best pictures will be taken from the side of the roads, especially in western provinces of China : Yunnan, Sichuan, Qinghai, Gansu, etc. .

My 2 cents...