What I get a kick out of is when stories have "grown in the telling." A series that was initially planned for three novels, gets expanded to four or five because it, "all just wouldn't fit" into three novels. Which is all fine and dandy at face value, by the way. The funny part is how the story always seems to "grow" in whole-novel increments (each commensurate with the page-count of the previous books). Nobody ever needs to add a novella's worth of material to get things "just right."
