Strange use of the word “Fit"

The Audio series “The Hitch Hiker’s Guide to the Galaxy” has the various chapters labeled as “fit,” as in "Fit The Thirteenth,” Fit The Fourteenth,” etc.

What meaning of “fit” is this?

I’ve always assumed that it’s fit as in spasm, paroxysm, convulsion, epileptic fit, and by analogy any sudden burst of activity, enthusiasm, etc.

But the OED says there is also an obsolete sense of fit meaning a part or section of a poem or song. As Adams took a BA in English Literature at Cambridge he was possibly aware of this sense of the word, and his use of the word in Hitchhiker may have been intended to evoke both senses.

Lewis Carroll’s nonsense poem The Hunting of the Snark is also divided into fits; Adams may have been inspired by this.

wiki says

Thank you - that makes some sense.

I thought you were going to ask about another odd (to my ears) use of “fit” in British English. Apparently, they use it to mean “hot,” “sexy,” or “attractive.” In my mind, someone can be “fit” (physically fit, that is, muscular, thin, not overweight, healthy, or something like that), and still be unattractive.