Isn't this a somewhat meaningless question? A light romance or fantasy novel takes considerable less time than, say, a literary novel. At least it does for me. With a literary novel you may need to think about what you read, puzzle out something, perhaps look something up, take a moment to admire and re-read a particularly well-turned paragraph, etc. IMHO such a novel requires more interaction on my part - which is part of the fun of reading it, of course
