I'm reading Sweet Valley High books right now. I don't know why, but I seem to be getting all the "special episode" books. That is, all the books which deal with heavy topics, like racism, drugs, alcohol, runaway teens, criminals, and others. This is opposed to the series' standard faire, which is high school dating and drama.
After reading enough of these books, I've come to the realization that they're all basically the same. A few of the details get changed around, but they're mostly identical. They're so much alike, I could make a template. Just like this:
The main character is a [boy/girl] who is a [junior/senior] and [new in town/a longtime local]. They have a [good/bad] [boyfriend/girlfriend/crush]. They are hiding a secret about [themselves/family member/friend/romantic interest]. They spend five chapters, lying about the secret over and over again, until things reach the breaking point. The secret is revealed, and there is a big fallout. The character has a change of heart, and a happy ending ensues.
The character's age determines which of the main cast members they'll interact with. If the romantic interest is a good crush, the happy ending is them becoming a couple. If the romantic interest is a good boyfriend, the secret reveal results in a temporary breakup, which is resolved at the end. If the romantic interest is a bad boyfriend/crush, the happy ending is the hero breaking up with them or telling them off.
Not EVERY special episode book follows this template, but enough of them do for me to notice it. If I had more time, I could probably make up a simple computer program that randomly generates a storyline based off this template. There's something like 100+ combinations here, especially if you add more details like "main character has [zero/one/two] siblings and [divorced/married] parents."