Reading Habits: Many Books

My currently reading pile. Three new books and one kind-of-sort-of-reread.

Reasons I have ended up with a multitude of books on the go in the past:

1. I leave books lying about the house, and sort of pick them up at random.
2. Holds keep coming in from the library. And, obviously, the moment a hold book comes in, I must start it ASAP. I get about a hundred pages (or two hundred pages) in, and another hold comes in the next day.
3. A book doesn't impress me. 
4. I woke up and grabbed the closest book, or found a book in my backpack/purse that I had been reading.
5. I'm just not in the mood for a particular world. Like not being in the mood for a particular food that you generally like. Except for your brain.
6. I'm reading something more dense, so I have a lighter read as well. (Like when I was reading The Silmarillion).
7. I have no attention span. There are gnats with better focus.

So, do you always have multiple books on the go, or do you prefer to focus on just one book at a time?

Here's a photo of my "currently reading" pile from last year.