Yes, a professor I had called it "cinnamon bun," and it's been a thing since at least the early 90s. Waterfall doesn't have to be end-to-end.

In my experience it's better to have more than a 2 week cycle though. I've seen it at 3 months and 6 months, both worked fine. Even if waterfall is end-to-end, it should still be broken up into phases for sanity checks.

Sure, but if they're on the same project it might be called something else.