The six beats describe one way of building momentum, not the only one. A novel can feel inevitable through pattern, image and voice without a single goal being stated, and some of the novels this chapter reads are built on refusing the chain, because their subject is a world in which causes do not hold or a person who cannot choose. A writer who treats the beats as a law will diagnose those books as broken, and will be wrong about them.
The model’s origin in a mid-century magazine market is not a reason to dismiss it. That market needed stories that held a reader across a break and through a session, and the model it produced describes a large part of the fiction written since, including a great deal its author never read. Knowing where it came from tells a writer which of its assumptions to question, chiefly its preference for agency and escalation, and which to keep.
Its value in revision is diagnostic. Run on a draft, the tests do not say whether the book is good. They say what kind of book it currently is: one that runs on the chain and has a broken link at a findable point, or one that runs on something else. In the first case the tests locate the repair. In the second they put to the writer the question the chapter has been building towards: if this book does not run on the chain, what does it run on, and is that engine strong enough to carry a reader to the end? A writer who can answer that has used the model well, whichever kind of book they turn out to be writing.
See also: the Reference coda; The Dialogue Exchange (Chapter 3), which takes the chain into talk.