4/4 of my PVG-BKK-PVG had heavy smoking, particularly noticeable up front and in a narrowbody (737).
2/4 of my JFK-PVG-JFK flights had some smoking but wasn't too noticeable unless if you are sensitive to smell like me.
This was this month (December 2018). No change from previous years. If anything, it was worse than my flights to SIN last year.
Also echoing the previous comments on bus gates for a fully loaded 777-300ER: happened 2 or 3 times for JFK-PVG-JFK. Absolutely ridiculous. Load factors were 90%+.
China Eastern is blacklisted for me for mileage runs. I'll move to Korean Air, which earns 100% MQMs now.