How I write two books at a time, and you can, too!

Can you write two books at a time? A friend of mine told me how she does it.  She alternates.  One book one week, the other book the next week, she says.  Her method more than works.  While one book cooks in the unconscious, I dream of new ideas. Awesome how this happens, isn’t it?  My books are somewhat related.  The larger book (in the 45,000-word range, Unholy Alliance) is a sequel to Deadly Alliance.  The second is a novelette (8,000-words) and has connections with my Alliance series and also other novelettes in a place author friends and I made up—Moonlight Cove, California.

What about you? Can you multi-task more than one book? How do you do that? Do you write a bit to both books each day, or alternate, or…?