I just used 144 hour TWOV out of Japan (KIX). At first the agent was confused when I mentioned the TWOV exemption. I showed her an IATA printout and after doing some work on the computer she pulled out a sheet with TWOV rules. She then pulled out a calculator and tried to figure out how many hours I was in China for. I'll be in China for 4 days so I didn't understand the need to calculate it. Anyway the sheet was in Japanese but clearly showed hgh and pvg as 144 hours but i didn't see if it mentioned that it is 144 hours starting at 0:01 the following day. So while you may be compliant you might need time to make sure the agents understand when the 144 hour clock starts.

Btw I thought I read there was a separate TWOV desk in hgh? I didn't see one and went to a regular checkpoint. Agent called someone else over who led me into a separate room where agents kept going in and out. They were friendly but was a bit intimidating. A couple of agents took pictures of my documents as she put the TWOV sticker in my passport. Seems some of them were unaware of the program or the process (not sure which and I didn't stick around to ask).

Another benefit of TWOV that I learned is that while a Chinese visa takes a full page, the TWOV sticker is only a quarter the size.