A lot of query letter templates say to mention other novels that are like yours, but how many stories should be listed?

Asked writers and a friend who has connections with the agenting business, and the consensus seems to be: more than 1, not more than 3. If you only mention one, then it seems like you didn’t do enough research. However, if you mention 5 then it just seems like you’re trying to justify your book’s existance. Plus, it takes up extra space. Two or three, it seems, says “I’ve done my homework and there are a goodly number of books like mine.”

My friend also said this: “Just make sure to put the most important two first and last, because the eye tends to read the first thing, then the last, then the middle, and often forgets the middle, especially when it comes to lists.”