Quick google search will show lots of motors at 1,000,000 miles on a single drain.
They are all running some type of bypass filtration and using oil analysis to keep tabs.
I've seen several on conventional oils, this is nothing new, but they keep very close tabs on things, and add bypass filtration.
Trucks Surpass 1 Million Miles Without an Oil Change
On small gasoline/ diesel motors there is unlikely any cost savings vs just draining the oil, but it is still fun (with proper monitoring).