KEEP AN EYE ON THE PREVIOUS POST- IT'S AN IMPORTANT ISSUE!
But in the meantime:
I think sketching is just as important as finishing a painting. Keeping loose and experimenting with technique, media, speed and ideas helps you grow. These are some sketches from my recent sketchbook- some took up to 30 minutes, others less than 10 seconds. I think quick-sketching shows a lot of life; something often lost if you over-work a piece. (for some reason I LOVE those old victorian/edwardian photographs)
I just put these, along with a few more sketches, on my website in the sketchbook section.