I used to work on one novel, one short story, and a poem at the same time. Then I switched to working on one book and/or item at a time. Now I’m back to working on multiple things at once. It’s a stretch of the mind, to be sure, but also a method of getting a lot done because you are multitasking. These days I usually have one personal project, something freelance, and something art-related all happening at the same time. Thus far, things are working out okay. This will probably change in the future as the project schedule changes, but until then, I’ll stick with this method of working.
On a personal note, I am looking forward to things slowing down a bit. Can only go hard for so long until you burn out and, frankly, that’s already happened several times over. Gonna need time to recuperate but this going hard is all part of my masterplan so you gotta do what you gotta do.