I host a weekly figure painting session at my studio. It's three hours of the same pose (with breaks of course) so that we can really slow down and take our time painting the figure.
I do like taking it slow and spending the time necessary to develop a painting, but most of the time, I really enjoy quicker sketches in these sessions. I used to have the model do two or three different poses in the three hour period, which I thought was just great for doing exercises in being decisive about colors and strokes, not to mention there isn't time to overwork the painting.
But it turns out, most of the artists who come to the sessions wanted more time on a pose, not less. So now we just have one pose. To satisfy my needs, I just move to a different spot each time, and voila! I have a new pose.
Sometimes I stay at the same spot, but shift my focus so that I'm doing a different study. In this case, I did a full figure sketch, and then a head sketch.
I may try a different color scheme, or different materials, or a different process. I really think you get a lot of bang for your buck when you do quick studies.
The above black/white painting and the two following are from the same session. I decided to work only in black and white. The first one is a 9x 12 sketch, using Ivory Black and Titanium White on oil-primed linen. I was basically interested in organizing the values into simple categories. No time was spent on modeling, really.
And then for the second study, I switched to a 20 x 16 sheet of cheap cotton canvas. This is more of a drawing than a painting. I started out drawing the figure with the brush, liked what I saw, so I stopped there.
And then I wondered how it would look if I kept going, so I did another sketch, from a different angle. It's still a quickie, may be 40 minutes on this one. Again, the value structure is kept very simple - no time to do anything more than simple.
Another day, another session. A simple color scheme, simple shapes. It's easy to fall into the trap of overdoing the details, especially of facial features. We feel like we have to make our painting look like the model. How many times have you said, or have you heard others say apologetically, "it doesn't look like him/her, but..." without being asked? Sure, likenessess are important, if you say so.
But since I'm not all that interested in painting likenesses, it doesn't bother me too much if my sketch doesn't resemble the model. I'm more interested in simplifying the shapes and forms. I'm more interested in not putting in details. I'm more interested in trying to get away with as little as possible. (I often paint only one eye, or omit painting the mouth all together)
If I end up with a nice painting that doesn't look like the model, that's far better than a poorly executed painting that nevertheless looks like the model.
Needless to say, a great sketch that also captures the likeness of the model would be ideal, but that doesn't happen to me very often.
Doing these quickies gives me a lot of opportunities to explore many aspects of painting, and I learn a lot from doing them. Pursuing detail or the likeness for three hours is not for me, unless I have a specific time-consuming problem to solve.