Not only do I switch from whichever work I am most enthused about at any given time, I do the same thing within the internal structure of each story (with novels, anyway; short fiction always gets written from beginning to end). It’s not unusual for me to skip from scene to scene in no particular order, although sometimes linear progression is easier. I tend to find that if I insist on working on something that isn’t pulling me with the same strength as something else, I start losing concentration. I actually am pretty good at knocking out large blocks of work on the same WIP before I move onto other things, but with the marathon-length novels I can’t sustain it. The major work I am writing ATM was one I began in 2016 but it’s pretty heavy going sometimes, and so I wrote a shorter novel when I decided to take a break from the longer one, and now I’m doing the same again with an idea I had over the Christmas period.
What I do find particularly useful when I put aside a WIP for a period of time, is that when I come back to it, it is with new eyes and I can more easily assess the flow of the writing, plus find whatever typos have crept in while I was looking at the larger landscape.