A common series length in YA fiction is three books, more commonly known as a trilogy. Many reviewers seem to have an issue with the three book set up, and often you hear the middle book criticised. This is such a common ordeal that there's even a name for this "condition", which varies from reviewer to reviewer but I call it middle-book-itis, though there are many other names such as middle book syndrome.

So I'm here to ask you guys what you think about trilogies. Below I've compiled a list of advantages and disadvantages of trilogies:

- longer than a duology or standalone
- not too long or short
- enough time for character development
- three books allow for a book of introduction, development/climax, and resolution
- you get used to most series being this length

- too short (leaves you wanting more)
- too long (not enough plot)
- could have middle-book-itis
- feels like a stand-alone/duology extended in an attempt to earn more money
- the whole thing could've been shortened into one more effective novel

As you can see, a lot of the advantages are disadvantages are just opposites of each other, depending on your preferences. And for this reason, I think it really depends on the reader and the series. For some books, I find that a trilogy is the perfect length for the story, but others fit it less.

What do you think about trilogies? Are they too long/short?