Don't remember distances exactly, but I believe I filled up every time on the way home from work, which was the same time every evening.
I tried to keep my variables to a minimum by only driving to work and. My side trips were usually kept to one to two trips per tank, which was 14 miles each way on a beltway with stop lights traveling no more than 60mph. (probably should've included that tidbit.) There is no way to control all variables but I tried to make sure they were at a minimum if I could help it.
My little experiment wasn't an attempt to be groundbreaking or the "be all, end all" on choosing your gas station. It stemmed from a conversation with friends about getting better mileage using other gas besides Sunoco because of the higher Ethanol percentage in their gas. I was just stating my results as more of a conversation piece than true fact. You can either drop your corn cob pipe in amazement or disregard everything I've said. It's no skin off my back either way.