Seems like there's momentum to get a sketchbook subforum under Blender, so I'll add to it.
I started doing Everyday's in November, took a short break to do The Engineer's Desk project, now back at it for a while. Everyday's for me are an awesome way to practice new skills, try things out without getting sucked down into the weeds of a bigger project, and just loosen up for the day. I spend 30-60 minutes first thing in the morning. I can't recommend enough giving Everyday's a shot.
I also put them on my website http://tylerjdisney.com/everyday/ and Instagram (@tylerjdisney).
Here is today's. The point was to learn/practice AO baking, which I did, but in the final image you can't really see it. Ah well, mission still accomplished.
All feedback and critiques are welcome.