The List of N Things
I bet you the current issue of Cosmopolitan has an article whose title begins with a number. “7 Things He Won’t Tell You about Sex,” or something like that. Some popular magazines feature articles of this type on the cover of every issue. That can’t be happening by accident. Editors must know they attract readers.
Why do readers like the list of n things so much? Mainly because it’s easier to read than a regular article.  Structurally, the list of n things is a degenerate case of essay. An essay can go anywhere the writer wants. In a list of n things the writer agrees to constrain himself to a collection of points of roughly equal importance, and he tells the reader explicitly what they are.
Some of the work of reading an article is understanding its structure – figuring out what in high school we’d have called its “outline.” Not explicitly, of course, but someone who really understands an article probably has something in his brain afterward that corresponds to such an outline. In a list of n things, this work is done for you. Its structure is an exoskeleton.
As well as being explicit, the structure is guaranteed to be of the simplest possible type: a few main points with few to no subordinate ones, and no particular connection between them.
Because the main points are unconnected, the list of n things is random access. There’s no thread of reasoning you have to follow. You could read the list in any order. And because the points are independent of one another, they work like watertight compartments in an unsinkable ship. If you get bored with, or can’t understand, or don’t agree with one point, you don’t have to give up on the article. You can just abandon that one and skip to the next. A list of n things is parallel and therefore fault tolerant.
There are times when this format is what a writer wants.
One, obviously, is when what you have to say actually is a list of n things. I once wrote an essay about the mistakes that kill startups, and a few people made fun of me for writing something whose title began with a number. But in that case I really was trying to make a complete catalog of a number of independent things. In fact, one of the questions I was trying to answer was how many there were.
There are other less legitimate reasons for using this format. For example, I use it when I get close to a deadline. If I have to give a talk and I haven’t started it a few days beforehand, I’ll sometimes play it safe and make the talk a list of n things.
The list of n things is easier for writers as well as readers. When you’re writing a real essay, there’s always a chance you’ll hit a dead end. A real essay is a train of thought, and some trains of thought just peter out. That’s an alarming possibility when you have to give a talk in a few days. What if you run out of ideas? The compartmentalized structure of the list of n things protects the writer from his own stupidity in much the same way it protects the reader. If you run out of ideas on one point, no problem: it won’t kill the essay. You can take out the whole point if you need to, and the essay will still survive.
Writing a list of n things is so relaxing. You think of n/2 of them in the first 5 minutes. So bang, there’s the structure, and you just have to fill it in. As you think of more points, you just add them to the end. Maybe you take out or rearrange or combine a few, but at every stage you have a valid (though initially low-res) list of n things.