FWIW:
When to change oil can be determined in testing labs.
For example, during the past 40 plus years, the military has followed an Oil Analysis Program especially for all vehicles issued to National Guard & Reserve Units where vehicles are used very sparingly & have very low mileage over a long period of time.
Military vehicle drivers start the vehicle & allow it to reach operating temperature, remove the dip stick, allow a little oil to drip in a test tube, whereby the oil samples are identified to match the vehicle & tubes are mailed off to a testing laboratory for results & instructions on whether or not to change oil in a particular vehicle.
Forgot the longest time some vehicles went without oil changes, but no limited use vehicle had oil changed every (6) months as recommended by oil companies & vehicle manufacturers.
One soldier/driver asked a fellow reservist Petroleum Engineer, "Won't the oil go bad after sitting in this deuce-and-a half (2-1/2 ton) truck for over (6) months?
Petroleum engineer replied, "The oil sat in the ground for several million years, why would it go bad when brought up above ground & placed in a crankcase."
My Dentist has a sign in his office which could pertain to recommendations on when to change oil:
"You don't have to floss all your teeth -- just the ones you want to keep!"
It would be interesting & most educational to be able to review oil analysis reports & test results for Model A's with limited use vs. Model A's with daily use whereby results would also include whether or not Model A's had oil filters.
Humble opinion, in Summary:
We would still have exciting Model A Oil War Discussions to contend with because some would never want to change their Religion & believe in the more modern scientific oil analysis results.