Join Date: May 2012
Location: Munich, Algarve, Sussex or S.F Bay Area
Programs: Mucci, BA Gold, A3*Gold, AA Plat, HH Gold, IHG Plat Amb, Marriott Plat
Posts: 4,164
I can confirm it is exactly as CWS stated. (Of course!)
I have done this several times, on through tickets as well as on separate bookings. And, it is 3 whole days, so you can stay up until midnight on the 3rd day following your arrival. All airlines are well aware of it and it is a very commonly used facility. Getting a Chinese visa, especially if required quickly, is often a PITA, especially of you are not in your home country at the time.