I have always found the sketching, or doodling, during the day helps me process problems I am working on at work. It allows my mind to wander a bit, taking focus off of the immediate issue at hand and gets me flexing some other parts of my brain as I ruminate on solutions to the work of the day.
Sometimes these sketches are part of a larger concept or sometimes they are just random themes that surface as I let the pen take over the page. I am rarely without a trusty moleskine sketchbook and my folio of drawing tools; I usually have several types of pencils, pens, and brushes ready to tackle any creative block while I am on the go.
Typically, over lunch, I will spend a brief bit of time concentrating on some specific sketch that is in service to a larger project that I am working on at the time. But throughout the day, in meetings, breaking from a task, or just waiting for others to arrive, I can usually be found passing those micro-moments with my head down sketching.