Moira, I also answered your question in another thread. Here's a brief summary of that one:
I have come to realize that my creative process involves a lot of experimentation and play, so I am always working on multiple projects at once. Sometimes I have lots of WIPs because I've committed to provide new pieces for shows, sometimes I have a lot because I'm in the process of trying new techniques and making samples to decide whether new techniques, materials or threads are something I want to incorporate into a larger piece. And I have multiple machines so I can leave them set up to work on different things as the mood suits, or as a deadline calls. I also use some techniques (like fabric painting) that require drying time so it makes sense for me to have other things I can work on while a piece is drying.
I also always have and always
will have UFOs. Most of these are things that I got started on and either got to a place where I just couldn't figure out where I wanted to go with them- maybe I couldn't decide if I wanted a border, or what kind of border, maybe I couldn't decide if I wanted to do some surface design work on them, etc. These get set aside and I let them percolate in my subconscious (similar to being forgotten about) for a while (like maybe years, sometimes

) before I hit on a solution. I also have a few UFOs that are partially pieced tops designed by other people where I just got really bored doing the piecing and couldn't make myself finish- my Bonnie Hunter ORL - the mystery from last year is a prime example of this and I don't intend to work on finishing the piecing any time soon- though it will eventually get done- probably several years from now

.
Rob