I think you’re also talking about one of Adams’ later books after HHGTG once his publisher was deep in hock for his advance.
They told him to hand over whatever he'd got:
"Douglas happily built his reputation for (at this stage, merely) sailing close to the wind when it came to publishing deadlines by telling interviewers that he had been ordered to literally stop writing and hand his manuscript over to a courier no matter where he had got to…"
— The Frood: The Authorised and Very Official History of Douglas Adams and The Hitchhiker’s Guide to the Galaxy by Jem Roberts"
He was famous for scraping or missing deadlines from the very start, and openly admitted to it:
"All of my life I've been attracted to the idea of being a writer, but like all writers I don't so much like writing as having written. … each time I meant to try to write something, I'd miss the deadline by two weeks."
The book was practically guaranteed to be a best-seller.
Having written several works without ever completing or publishing any of them, I find this comment from Adams particularly resonates with me. That said, I’ve had success with a narrative podcast, which is heavily influenced by his genius—his wit and comedic writing style shine through. While I’ve always admired what he brought to the sci-fi comedy genre, in hindsight, I probably owe just as much gratitude to his editor and publisher.
Considering how much he loved everything else and how well he was able to do things like radio shows or video or inspire text adventures, I do have to wonder if forcing him to write books was pounding a square peg into a round hole.