The one sentence paper [closed]

Solution 1:

Usage isn't governed by rules: usage creates rules. And then breaks them. And creates new ones. And so on, ad astra.

And, the more creatively and elegantly a rule is broken, the more likely it is to be imitated, "paid homage to", derived from, and variously bent, folded, mutilated, and spindled, til the new way becomes an established trope, and then a rule unto itself, vigorously defended by prescriptivists from the very highest parapets of the ivory tower.

So the answer to "how long can a sentence be?" is "however long you can get away with", and by "get way with" I mean construct in such a way other people will find compelling and convincing, and ultimately worthy of copying.

In terms of usual suspects cited, see for example this Barnes & Nobles Reads column:

There’s Molly Bloom’s 36-page, two-sentence monologue in Ulysses, or Victor Hugo’s 800-plus line [sentence] in Les Misérables.

Proust is also often cited as a loquacious author, regularly emitting 398-, 426-, 447, 599- and even 958-word sentences.

As for the current record holder, as detailed by 5 Wonderfully Long Literary Sentences, via @ab2 in the comments:

[the] record has long been surpassed, in English at least, by Jonathan Coe’s The Rotter’s Club, which ends with a 33-page-long, 13,955 word sentence.

For more engaging examples, it's worth digesting the curated list of 7 beautiful run-on sentences in the B&N blog.