144 hr vs 72 hour exemption

There are three separate transit without visa timeframes. 24, 72 & 144 hour. Shanghai was the first to extend the 72 hour time to 144 hours. Beijing later switched from 72 to 144. some pages here still reference 72 hours when they discuss Beijing but that now longer applies. Beijing you either qualify for the 24 hour multiple stop transit or the single stop 144 hour transit. More and more cities will switch to 144 hours from 72 in the future.

Shenzhen for example was one that did not allow even 24 hour transit but recently added it with some stipulations. Guangzhou for example only allows 72 but is in process of joining Beijing, Shanghai and Liaoning provinces in increasing the timeframe to 144 hours.