Sketching is the corner stone of creation, be it painting, Illustration, design… I’m pretty sure countless works of art sparked from a tiny scribble in a Sketchbooks, somewhere. This include films and animation works but it doesn’t stop with the visual arts. Even some unillustrated books and literary works started with Sketches. And it applies to a lot of other fields too: webdesign, architecture, planning, etc. In a sense drawing is akin to writing. Taking notes helps us to order our thoughts but we can also use it to trigger ideas.
Have you heard of automatic writing? Maybe something similar, although not in the literal sense, is at play when we are drawing Sketches.
“Take a Sketchbooks everywhere” is great advice and I sure have one with me everywhere I go. Actually, I repurposed the US Army Rifleman’s Creed, to say the same thing.