Building on thoughts posted by Lawrence and Doug Bowe, it seems there is no general rule of thumb. There have been good duos - a good book and a good corresponding flick. But often enough, if you’d read and liked the book, the movie was a bit disappointing. Lawrence seemed to me to be pointing out a scenario where a book has a good premise and had some other goodies, but is poorly executed overall and those responsible for the film adaptation provide the artistry of implementation that gets the job done. OTOH, when the author of the book is quite good at imparting the imagery, a prior reader of the book is likely to be somewhat crestfallen by the movie interpretation, having already fixed a visual story in their mind.
For me the paramount example was Dune, a book I encountered in the late '70’s and absorbed enough to produce an ethnography thereof for an anthro class. I guess I spent too much time with the book… the movie bored me to tears.
Doug’s comment regarding novellas struck me as a thought on the possible middle ground for those oh so rare successful duos; perhaps the medium of the novella provides a good author with a platform that successfully displays their premise and their descriptive abilities, while not constraining the filmmakers enough to disrupt their craft or conflict with the readers’ expectations.