The more one reads, the more one starts to see narrative similarities between books. Sword and sorcery and urban fantasy are particularly noticeable with how closely the stories resemble each other. You know what? That's fine, there's nothing unusual about it and it certainly isn't a measure of quality in any way, shape or form, for good or for ill. For those of you who think that any whiff of parallels between books is “teh wust ting evah” I would invite them to try petting the more rambunctious of my two cats. She has a vendetta against toes.
Now narrative formulas get a lot of flak for being, well, formulaic. I've heard ramblings about how such things are ever so restrictive and that they kill creativity. I've also heard that formulas as a rule are boring and repetitive.
Let's examine that repetitive charge first. Like many things in the arts, a lot has to do with how you see a formula in the first place. I would posit that the average person who uses “formulaic” to (usually) denigrate whatever it is has something very specific in mind when they do so. For example a “boy meets girl, girl is stolen away, boy must win girl back” type of story may very well have a formulaic sticker slapped on it. Sometimes the person uses it against a particular genre to sound smarter and snootier at the same time. Romance is frequently a favorite target for such things, but all the genre fiction gets hit with this periodically.
So are there stories that get repeated over and over? In short, yes. Is this a horrible thing that must be stopped at all costs? Not so much. Why? Because the repetition indicates that a particular storyline is important to us in some way. Think about how many times the Bad News Bears has been rehashed, remixed and reinvented. Each iteration follows the same basic outline of misfit underdogs banding together and working hard to finally kick butt and take names, but some explore different side roads or try to appeal to a slightly different audience than the versions that came before it. Now think about what that storyline basically says: working together and putting in the practice will get you places. It's something important to us and we keep telling ourselves these stories to keep ourselves going. Since each iteration ideally differs from all the others in some way, this allows a broader audience to engage with a story and get something out of it. In fact there are no story formulas that cannot stand having a new spin put on them and there are myriad ways in which to do it. Star quarterback boy meets zombie cheerleader (because everything is more fun with zombies).
Now looking at formulas in the context of narrative structure you will start to see a few trends and patterns. The omni-present journey of the hero and the so called three act structure are the two the immediately spring to most minds. Just as an exercise, tell someone everything that happened in your day at work. Congratulations, you just used the journey of the hero format! One can play with it, leave some parts off, come up with new ones, even kill the hero at the end, but I would posit that the journey of the hero is so pan-cultural that it is arguably hardwired into homo sapiens as the way to pass learned information from one generation to the next. For the love of the smell of vintage books, history tomes use it! How else would you get so many people across so many cultures relaying stories to each other in such a similar fashion if it wasn't intrinsic to everyone?
So the next time someone tries to throw a “it's too formulaic and therefore awful” accusation at some story, ask them how their day was. Then call them on how they used a formula to tell you about it and offer your sympathies for what an awful day they must have had as a result of said formula.