It seems more likely that we are all biologically predisposed to function badly on such a schedule.
Some people probably deal with the deficits better than others, but all of the "positive" results from something that extreme I've heard of are subjective and self-reported, so not worth much as evidence. There is, however, lots of empirical data about loss of cognitive function due to sleep deprivation; to be fair I don't think any of the studies I've seen targeted precisely that (self imposed, cyclic) sort of pattern. On the other hand, none of that research suggests a good outcome would be expected. I'm not referring to all sleep patterns here, just those that rely on very short cycles, e.g. 20 min.
I've posted this challenge a couple times here, so it's as good a time as any: Has anyone done the Uber sleep schedule for, say, at least a year, and preferably still doing it?
(Caveats: I recognize there is significant sleep variation in humans. Science has confirmed this, even if it doesn't know why. I also believe in "bi-phasic" sleep of shorter nights and significant naps, again, this has been established reasonably well. This isn't generalized skepticism, it's specifically the Uber & other variants that I've never heard even solid anecdotal evidence for.)
I agree - I feel that trying it for a few weeks or even a month or two isn't long enough to really know if it works or not.
I tried a 28 hour day cycle (awake for 20 hours, asleep for 8; 6 day week) for a few weeks when I was in uni (as Mondays through Thursdays had me awake at relatively normal times and this suited my lecture schedule at the time) but then other obligations knocked me off schedule for a few days and I reverted back to normal. I feel like it could have been successful longer term, but I didn't do it long enough to know for sure. I guess the hardest part is making sure other things don't interfere.
As far as I can tell (without doing any sort of comprehensive survey), I think most people who do this regularly are people who cross oceans solo, and they only do it for that period of time.
I'm willing to tack on to my caveat list that it can be possible for a brief period of time. Since we know that no sleep leads to death, and people have clearly done Uber for longer than that threshold and not died, it can clearly be done for a period of time and you stay alive.
It's just that there does not seem to be any hope of doing it indefinitely. Sad. My personal biases and desires, like many here, lead me towards really wishing it could be, but I just don't see the evidence.