Should Writers Work on Multiple Pieces at Once?

While studying writing, I found this website that gives writers advice.

The first thing that Henry Miller says I should do, is work on one piece of writing at a time.

For me, this is the one thing I don't do. I work on multiple pieces of work at one time. Personally, I get blocks on my longer works, and need to write something else to give my brain another direction. That's just how my though process works with my fiction.

Sometimes I take a break from some plot to write a short scene or story. I've figured out that's basically my plan with one of my stories, completely changing my writing style.

I do finish things. I've just finished my story about mermaids, and it's in the editing stage. But working specifically at that one piece of writing, even with an outline, can become stale for me. I have so many ideas flowing, some of them short pieces telling me about my character, and then some of just smut. Either way, I'm going to jump back and forth.

And on top of all the fiction, I also write my opinion pieces down, and those also give my fingers some time away from writing made up stuff.

This is something that I know will always be a part of my style. Do a lot of writers work on multiple things at once? Or is the majority in the single idea mindset?

I guess that's it for right now. I have a lot of writing to get back to.