A whole lot of organizations, particularly gelled teams at them, do some variation of "plan, iterate, ship": https://blog.pragmaticengineer.com/project-management-at-big...
AGILE consultants did not invent iterative development, by the way.
I have never seen any process actually followed that looks like the AGILE consultants' caricature of "waterfall". The more serious you get, though, about defining requirements up front and making sure you meet them, the more your process will look like traditional systems engineering and stage gates. This does not preclude iterative work - the buzzword decades ago was the "spiral model".
in my opinion, it feels more like agile than Agile™
ShapeUp, as n42 commented - https://news.ycombinator.com/item?id=31534642
Product Development Flow by Don Reinertsen - http://reinertsenassociates.com/books/
Queueing Theory - https://en.m.wikipedia.org/wiki/Queueing_theory