I’ve previously talked about how I often take a lot of notes, and how writing things down has been very helpful for me to work through problems and come up with ideas.
In the past I used the traditional notepad and pen, and must have over a hundred of them going back through my career.
I went through a phase of using hard-backed A4 size pads, then settled for many years on a particular hard-backed A5 size pad.
More recently, I’ve been using the reMarkable writing tablet (https://remarkable.com/) – which is designed to mimic the feel of writing on paper and allows for the storage and indexing of many thousands of pages of writing and sketching, both in its own memory and in the cloud. The main advantage I find is being able to access all my previous notes in the same place, without having to remember which pad they were originally written in.