I spoke with my dad about this and he feels the same way. When I read a book in a day, sometimes I regret it because it feels like I haven't taken enough time to appreciate the way the author has crafted the sentences and the way the story has so beautifully been told. My mom, on the other hand, will start a book at 11 at night and read through till 1 in the morning until she has finished the book.
I understand that there are some books that are so fast-paced that you simply can't put them down. I've often had that as well. But sometimes I read so fast that I actually miss out on parts of the story because when I go back and read parts again, I am shocked by how many things I've actually missed.
Do you prefer reading slower or faster? If you're going through a book too fast do you will yourself to read it slower?