Where does the story end?

On a friend's recommendation, I recently starting reading the Thursday Next series of novels by Welsh writer Jasper Fforde. It's about a brassy young woman working in a futuristic England, though set in 1985 (literary pun intended on the part of Fforde), who I'd describe as part Laura Croft, and part Bridget Jones. The series is composed of five novels, and a sixth may be on the way in several years. The novels would make fun reading for any bookworm well versed in the classics, as the story is burdened with an overabundance of quirky literary allusions and references.

I enjoyed the "ooh, I get that obscure literary reference, aren't I clever!" feeling that I got reading the first novel (The Eyre Affair), but now, a quarter of the way into the second of the five in the series, I'm beginning to find it a bit annoying.

But because I feel compelled to find out what the end of the story is, I'm going to hang in there, and read through all five. Not that these novels are bad, per se, but just....long. I feel like if Ffordes editor had been on top of their game, they could have saved us all a lot of time and unnecessary prose.

So this got me thinking about the nature of series', and their increasing popularity as of late. Harry Potter, The Chronicles of Narnia, His Dark Materials....what is so unique about a story that it cannot be contained within just one book, but must spread out across half a dozen or so brick-weight novels?

*Disclosure* J.K. Rowling could go on with Harry Potter for as long as she lives, and I'd be a happy camper*

So my real question is, where does the story end? Many writers say that they could go on forever about their characters, but they choose to end their novels at a point that they deem appropriate. Then some other writers will simply ramble on about the same people for thousands of pages, given a multiple-book deal. For some this is appreciated, and as for others, well, let's just assume that their agents are VERY good at their jobs. 

Some writers have described going through a grieving process when they finish a novel. They have spent many months with these characters, and to let them go is akin to losing a member of the family. I know that as a reader, I have felt this at times when I've become extraordinarily immersed in a particular story, and I'm reluctant to say goodbye to these characters that have become a part of my daily life for a brief period of time. Yet, like a party, I would sometimes rather leave a story early, than stay too late. Because once the lights come back on, and the streamers have fallen to the floor, no matter how good the party was, I wind up feeling tired, disappointed, and relieved that it's all over.

This is how I'm starting to feel about this series, and series' in general, excepting Harry Potter. The initial buzz of excitement has worn off, and now I find myself checking my watch, and hoping last call will come sooner rather than later.