I always have 3 books going at once.
I just read Barbara Nickless's "Dead Stop" on Kindle while reading hard cover Michael Connelly's "The Waiting". Both involved ultra-strong women cops and both involved cold cases. Both super-excellent. But I had to concentrate quite hard on on not mixing up the two protagonists and their teams. My third book? On audio and it may be years before I finish it: "Southern Man" by Greg Isles.
Yes, I'm quite the fiction reader.