I would actually give an allowance of half a day. The weather has been awful of late and flights have been diverted, not forgotting delays in parking the aircraft and also departures, etc...

Never take anything for granted in China...it's just not worth the stress and worry and then money you will have to spend later getting/paying for another flight. If you really really want to be safe, book a connecting flight the following day.

Fly in, check into a hotel, get some sleep and then get on your next connecting flight the following day.