Zackly. And if I recall, PP writes SFF, so the chances are that's a lot more world-building and a lot more words. And then the putting it aside for a week or two, and then the re-reads and edits, and the polishing, and the betas (if PP uses betas, and as a new writer I think it would be a good idea to use betas) and in the middle of all that there's living and publicity of some kind, even if it's mostly done by the publisher, and taking time to create the next book, and polish and edit the last book and also - keeping fit and having a place of some kind in society if that's a thing - even if it's just shopping for groceries and reading the papers.Honestly, I do, too. I have read some pleasant novellas by writers who put things out several times a year. 15-20K words. Maybe that could work? I wrote one of my short stories in about four days before handing it off to an editor - 2500 words, and I had maybe three back-and-forths with the editor before it was finished. So call it two weeks, start to finish.
I can draft a book in 3-4 months, depending (although it's been a while since I've done that). Revisions and edits generally take anything from 1-4 years.
It's just vanishingly unlikely that anyone could write (where write means have written) four books a year - esp SFF. It's not a helpful expectation, I think.