Sketchbook dates are approximate. I tend to go back and fill in empty gaps, when I start running out of pages and sometimes I doodle from both ends at the same time –which all makes for a difficult archaeological challenge for those historians of piss-poor artwork out there.
Also, since I tend to use my sketchbooks for general note-taking and diary-esque scribblings, I sometimes have to leave scanned pages out of these uploads, in order to protect the guilty. That’s why some 'sketchbooks' I upload only seem to have a couple of drawings in them. The rest was deemed 'not fit for public consumption'.