All the time, I'll go three or four books at the same time, all the time. At the moment it's two novels, a short story collection, and a non-fiction book. Each night before I go to bed I'll think about which of the books I want to keep reading, which changes every night depending on my mood, and I just pick up where I left off and enter that world again. Occasionally I'll pick up a book that is so captivating that it's the only book I'll want to read, and in these cases I will enter a monogamous reading relationship with it until its inevitable end.