Depending on where you stay in Yongcheng, a free airport shuttle might be a two-way trip to and from the airport or it could be just a one-way trip to your hotel.
How often will the shuttle run?
It depends on the hotel you choose to stay in Yongcheng. The shuttle may run 24/7 or it could be restricted to certain times a day. Check the hotel's policy on Expedia before booking your stay.