Do you read multiple books at once, or are you one of those readers who only reads a single book at a time, and reads it straight through?"
An interesting question: I've talked to a lot of people who have an almost pathological fear of reading more than a single book at a time.
Some of them seem to fear that if they read more than one book at a time, they won't be able to finish them both (or them all). This might be a concern if you read only library books that are the 7-day borrowing list. If you own the books, though, this shouldn't be too much of a problem.
Others express concern about the plot lines (or the subject matter, in the case of nonfiction) running together.
I don't understand this one, either. Almost no one says, "Hey, I'm watching The Walking Dead this season, so I refuse to watch Justified, Mad Men, Dallas, or Grey's Anatomy. I don't want the story lines running together!"
From my perspective, reading multiple books at a time is really no more problematic than tuning into multiple television shows at a time. Speaking of which--I don't watch much television; so I usually have multiple books open.
My average number of "open books" has grown in the past few years, as I've begun reading books on Kindle, and listening to books on my two iPods. I also usually have an audiobook in my car's CD player.
This doesn't mean that there are no limits here--although the exact limits can vary according to the profundity of the books I'm reading, and my other time commitments.
I generally avoid reading books that overlap in obvious ways. For example, if I'm reading Nicholas Nicholby, I probably won't be reading Middlemarch at the same time. Yes, I know that Dickens wrote the first book, and George Eliot wrote the second; but both are thick, nineteenth-century English novels that might take me several months to work through while I'm also reading lighter fare.
On that topic, for me there are books that are "fast reads" and others that are "slow reads". I can read an entire John Grisham novel within a day or two. On the other hand, older novels, and more "serious" books can take me much longer.
To cite one example on the long side: It took me almost two years to complete Edward Rutherford's The Princes of Ireland. To begin with, this book is 800 pages in length. It is also slow-moving, even for a historical novel.
Nevertheless, I didn't want to abandon it; so I read it in short segments, when I was "in the mood" for a story that moved a bit more slowly. I no doubt finished several dozen books while I worked my way through The Princes of Ireland.