Rhodia dotpads have been my go to "working notebook" or "Bullet Journal". It is more the former at the moment. In the past I have used LT1917 dotgrid notebooks, but I recently moved to dotpads partly because they're much cheaper. And also the ability to rip out pages as I'm done with them is great.
What I use it for is to write lists for stuff I'm doing right now, to write drafts for lists of tasks I'm going to add to my to do system and capturing things.
Very useful to avoid context switching, if you have a messed up brain like mine. And I also use it a lot to plan stuff I later add to my task manager.