It's easier to develop your superreading and dipping and skittering skills on non-fiction books. That why when you move to novels you have a skill that allows you to move through the book from beginning to end using all the skills.
Rapid reading is closest to traditional reading in that you begin at the beginning and end at the end. The speed at which you read throughout varies, from rhythmic perusal to skittering to SR&D and occasionally it will be almost as fast as PhotoReading for a few pages (deemed not that important or interesting to you).
How long it takes to finish a book is always up to you. Don't compare to others first establish how long it normally takes you and then see if you can at least halve the time. (You still want to enjoy the novel don't you?) The more you use it the faster you see yourself going through any book.
AlexK