" Do you prefer to stitch on a rotation or one project at a time?"
I really don't have a preference. I have done both and both have their advantages.
Rotation removes some of the boredom that can arise when stitching on a single LARGE project. It is particularly helpful to intersperse stitching on a large BAP with smaller pieces (which might give on the felling of accomplishment when the small piece is finished), a piece with different stitchery demands (like speciality stitches, beading, etc.), or even a different BAP which, depending on how long the original BAP has been "in progress", may have a design more in tune with my taste (although this is usually why a piece becomes a UFO in my stash --- I started something new that appealed and all of a sudden, the old piece is no longer to my taste!)!
Often, when I do stitch on a large BAP, I can get on a roll, and it hurts my stitching mojo if I interrupt that roll by stitching on something else: I often lose my place (no matter how carefully I mark the charts). And sometimes I find that once I get onto something new, I really really have to work HARD to go back to that BAP--- it's appeal gets lost in the thrill of finishing smalls, etc.(see also above re UFOs!).
Again, in October, no stitching whatsoever. Sorry...