My wife always tells me that I waste money when buying books. If I am really into the book, I can finish it in a matter of hours depending on the number of pages.
The Lord of the Rings Trilogy though (I had a version that was combined into one book), took me three nights of reading before I finished it.

It's not wasting money though, I re-read religiously. I must have read each book in the Safehold Series by David Weber(currently my favourite series) at least 3 times by now, I guess I really enjoy his writing style as I've read most of his series (Honor Harrington, Dahak, War God etc) and I've enjoyed all of them but I only maintain physical copies of the Safehold series on my shelf.

I still classify myself as a casual reader as I don't always read, there are whole weeks where I don't have the time to pick up a book or ebook.