It depends on your purpose for reading a novel. If it's for pleasure you don't necessarily want to go through it at lightning speed.
If it's for school or literature studies then even in regular reading you would probably spend longer with it than what you would with a novel. Since in reality you are expected to read the novel 2 to 3 times to get the information needed for examination questions.
Sure you can get a novel finished a whole lot faster, the target that is reasonable is 1/3 the time it takes you to currently regular read such a book on average. Non fiction can be a whole lot faster.
Indeed it does come down to what is your purpose, are you taking regular breaks to check that you still are on purpose or have you allowed yourself to slow down to regular reading.
Usually when you read a novel for study, you are expected to notice things like plot, setting, era, characters, theme, message (whether it's moral, teaching or just informing), symbolism, language and imagery provoked by the authors writing. Depending on your purpose these would raise questions you can ask whilst activating the novel.
Alex