I do feel this falls under "personal whim". The games release when Bethesda feels they are ready. Just because you can map that to a interval of time doesn't mean that the time between games decides when they are released.
Like, Morrowind was properly delayed, it was supposed to come out in 1998. But as no date has been announced for TES VI it makes no goddamned sense to say it is delayed. It's like saying NASA's manned mission to the moons of Jupiter is behind schedule based on the Apollo program. No schedule exists, thus it is literally impossible to adhere to one.