My standard operating procedure is that at the end of each day, I scan any sketches I made that day, whether or not I plan to upload the image (I figure it’s simply prudent for the sake of preserving possibly fugitive media or, heaven forbid, in case of a lost or destroyed sketchbook).
The exception is my catch-all sketchbooklet, which is the small, handmade one I keep in my bag at all times. The vast majority of the sketches that fill it are portraits I’ve made while riding public transportation – just basic practice sketches, many of which end up unfinished because my “victims” got off the bus. With those, I wait until the whole booklet is full, and then digitize all the pages at once. Here are a few sketches from the one I filled during the past three months.
Incidentally, it’s the first of the sketchbooklets I made with my more refined process, and I’m pleased to say it held up well carried daily in my bag – it shows hardly any wear at all.