The Rule of the Odds

Who here reads? I know I do. I write, too: check out my other blog here. When someone reads, they typically plot in their heads what they want to happen and who their favorites are and what they ship, and so they get these dramatic FEELS. But thats not really what I'm talking about right now. But in reading, favorites are always evident... so let's talk about favorite books.
But more specifically, I want to talk about favorites within a series. For instance, my favorite Harry Potter book was Order of the Phoenix... and my favorite Percy Jackson book? Oh my! It's The Last Olympian! Why is this so amazing? They are both the fifth book in their series. And in all honesty, I don't think that is a coincidence.
So now we get to the title of this post: The Rule of the Odds. The Rule of the Odds states that the best books in a series are always the odd-numbered ones. Don't agree? Well, listen to this logic before you go out and whine about me.
Okay. The first book is always phenomenal, right? Right. Maybe it's actually a pretty suckish book compared to the rest, but it has to be good enough to get you to read the next one. Then comes the second book, which might be a little better written, but was mostly just written for the sake of having a sequel, and it's never quite as great. So, if at all possible for the author, a third book is written. Now, this third book is a little more well rounded than the others. By now, the author really does want to write these, and he or she has gotten to know the characters a lot better, and everything is just a little more right, and sometimes the author feels a little more free to do something stupid and crazy and it gives the book more depth. But sometimes that stupid and crazy thing really, really SUCKS. A case can be made with Mark of Athena, the third installment in Rick Riordan's latest project, the Heroes of Olympus series.  Now, I don't wanna give out any spoilers, but... it has a TERRIBLE cliffhanger. Or, Rickhanger as some fans have renamed it. That was one stupid and crazy thing that didn't turn out right, and so Rick (I mean the author) has to write a fourth book (right, Uncle Rick?) So, a fourth book is written. Now, this book feeds the same purpose as book two, except by now the characters are a lot more developed... and a lot more things have gone wrong, i.e. the stupid Rickhanger in MoA that tore apart the hearts of millions of fans all over the world. Thus, the fourth book is either phenomenally better than the second, or tremendously worse. But then we get to the fifth book, and by now the author has already written four extremely successful books (or successful enough to want to write and publish another), so he or she has learned what works and what doesn't, and unless they want to be extremely amazing like J.K. Rowling or Lemony Snicket (or are writing a trilogy in which case they are done, bye, later skater dude, or tried to write a trilogy and just couldn't stop so they wrote a fourth too in the case of Scott Westerfeld's Uglies series), this is their last book with this set of characters and back stories and this world (unless they take the Warriors route and write a bunch of sequel series, which is a concept no one except maybe Rick Riordan has seemed to be able to grasp). So, of course they want to make this great and end with a big bang. Whatever the case, the fifth is gonna be amazing. It's inevitable.
I'm going to stop now with my in-depth explanations, but you get the idea. This pattern repeats itself through out the whole series. Of course, series with a plethora of stories, such as the Nancy Drew mysteries or Magic Treehouse (maybe even A Series of Unfortunate Events if you want a more grown-up example) don't exactly follow this pattern, but the idea could still be there, especially if only one author is working on it (case in point: The 39 Clues).
Now I've explained this to you to the best of my ability. And maybe you still don't agree, maybe the second Harry Potter book was your favorite, and maybe you absolutely despised the fifth Leven Thumps book. Not my problem. But you have to agree that the logic is all there, and that even though The Rule of the Odds maybe isn't a die-fast rule, the concept of it is almost always there. Just some food for thought.
I still have other book patterns and unspoken rules I've noticed through the years (such as book color), and I bet you do too. So here's my question: What do you think?