I enjoy working in a sketchbook!
For me it’s a great way to keep a log of the places I visit. It’s my impression of the view, it can be exact or a selection of the “best bits.” No two sketch books will be the same, everyone records their view differently.
Once you master getting the scale right then placing your chosen view in the page is really easy. It’s fun to use both sides of the book as one page giving you a 180 degree view.
By adding text, whatever you choose to write, will add another dimension. It can be descriptive or anecdotal, it’s up to you.
Keeping a sketchbook as exercise for drawing and painting skills is good. Or using your sketch as a presketch for a painting even better. Formulating ideas by trying out and exploring a drawing, compositional ideas is really good too.
Developing an idea though several scenarios.
Perhaps devote a whole sketchbook to one particular topic as a body of research.