For reference, I change the oil in my main car at 10K or 1 year, which ever comes first. I usually make it about 10 months.
With that said, I've been driving the MG to work a decent amount lately and I might make 1 year before I make 10K in the other car.
Some days, I might only drive to work and back, which is 10-20 miles(round trip) depending on the route.
On nice evenings, I might take an evening drive in the MG and can easily do 100 miles or better in an evening.
Running errands around town can add 30-50 miles easily depending on where I need to go.
I will typically do 150-200 miles on one vehicle in a weekend.