Reason have looked for other supposedly longer lasting oils, whether correct or not, is it seems natural mineral oil seems to become darker sooner which I assumed with my lead foot meant it was breaking down.
Looking at Irv Gordon's habits would be a great starting spot, except that he used dinosaur bones and changed every 3k miles as has been pointed out. So it doesn't really tell us much about long life oil.
Longer drain intervals are more prevalent in Europe, mostly because their oil is designed for it. Or maybe vice-versa. (See
here for a reasonably good explanation, though admittedly it's written like an advertisement.) BMW is explicit in the LongLife specs (LL-98, LL-01) and VW has theirs (5xx.xx) and Mercedes also. (See more on specs
here and
here.) If European 10k mile maintenance guidelines are followed while using oil available in the US which is formulated for different priorities, sludging can take place. (See
here for a description, and
here for interesting pictures.)
There are many oil choices that meet the Euro spec, and they typically proudly proclaim that on the bottle. None are cheap. But they work really well, and you can easily get away with longer drain intervals. I use the color of oil on the dipstick as a guide to determine what a particular engine / particular driving conditions calls for -- the less blowby, the more slowly it gets contaminated -- but most of my fleet seems to be happy with ~10-12k so I've settled on 10k because the odometer is really easy to remember. I change the filter more frequently -- I can tell when the filter can't handle it anymore by the behavior of the oil light / gauge upon startup, it changes very subtly at about 6k-8k depending on conditions, and a fresh filter brings back the almost-immediate extinguishing of said light.
Whenever I have a valve cover off, be it 150k or 250k miles, everything inside looks clean as a whistle. If I have the heads off (or put a borescope camera through a spark plug hole), I still see cross hatches on the cylinder walls. And every vehicle I've been in charge of maintaining runs like new. I'll take that as a win.