I've always carried a back pack, briefcase or something like that.
As an adjunct instructor and training instructor I needed it for books, notes and things I used to teach.
As a ER tech I kept various items in the backpack including notes, medication reference books etc.
As a nurse I keep my nurses note reference guide, pharmaceutical drug reference guide, and other such items in my wheeled briefcase.
I can't think of a single co worker that doesn't carry a backpack of some sort from pharmacists, physicians, nurses and managers.