A common saying that the penultimate book of a series is often the weakest probably came first from The Two Towers.

Title: The Fellowship of the Ring (The Lord of the Rings, #1) Author: J. R. R. Tolkien Published by: Ballantine Books Published on: 1994...

Title: The Hobbit, or There and Back Again Author: J. R. R. Tolkien Publisher: Harper Collins Date of Publication: 21 September 1937...