I did three cars are once last month:
2005 Ford Five Hundred: 6 quarts of G-Oil 5W30, Motorcraft FL820S filter. Lots of suburban and city driving. OCI: around 5000 miles.
2005 Mitsubishi Lancer Oz Rally: 4.5 quarts of G-Oil 5W30, Purolator Classic. OCI around 5000 miles with mostly city and suburban driving.
1999 Ford Taurus: 5.1 quarts of Valvoline NextGen 5W30, the remains of G-Oil from Lancer above, and I re-used the oil filter that was installed by MIDAS on the previous oil change. The filter was used for only 1500 miles, and the current OCI will be about 3,000 miles, so I thought it's alright to reuse. This one was problematic because I don't own a filter wrench and the filter did not cooperate. The last oil change was done at Midas (it was a freebie) 1,500 miles ago. Lots of short trips.