Forgot to post my experience using TWOV. I did this 2 times a few months ago on outbound and inbound flights from LAX-PVG-HKG-NRT-PVG-LAX. Outbound, I was purposely stopped for 3 days in PVG with TWOV and inbound, china eastern (consistently done this) delayed my flight from NRT-PVG and missed PVG-LAX connection. Stayed once more night in PVG with pleasure, hitting nice bars in nanjing lu.
TWOV officers were very friendly and efficient. Very pleasant experience. They just needed to see the ticket. I only had a camera shot of china eastern staff monitor, because china eastern is just a very bad airline - made me wait 1 hr to get new ticket from PVG-LAX and no print-out. But, TWOV officer honored it with no issue.