I do all sorts of things. I do things where I need to really concentrate. Writing rituals, reading non-fiction, artwork, and more. All of these I consider deep work because they foster my creativity and introspection.
I believe that it is a matter of preference. I use a Waterpik in the morning and floss at night. After flossing I rinse with a little water and mouthwash to be sure that I got all the bits out of my mouth that the floss loosened.
I save the Deep Work habit for my most thought-intensive work requiring the most focus, which in my case is writing my dissertation.
Reviewing my most difficult files to confirm background facts, positions of the parties, items and tasks relating to upcoming deadlines and general strategy going forward