For my in-studio landscape painting class, I usually spend about 45 minutes to an hour doing a demo on a different subject each week. Obviously, that's not a lot of time and I don't expect to do fully resolved paintings on the spot. I'm usually talking about some specific aspect or another, and I'll paint and talk until I make my point.
If I think my unresolved painting has potential, I'll work on it later in my studio and bring to to a satisfactory finish. This may take an additional hour or five, for a 9 x 12 painting (my usual demo size).
When I did this particular demo (above), my topic was simplifying complex things like cars, using atmosphere. I didn't spend too much time on composition or drawing, as you can plainly see. But I thought there was potential and I didn't want to let it go so I started reworking it later, when I was alone in my studio and away from any pressure to perform.
This is what I ended up with. It's changed quite a bit. I love the medium's capacity and tolerance for making big changes!
The placement of the figure is unconventional, and I kept moving it around but couldn't resist playing with fire. In the original demo, it's placed more predictably, and while it's sloppily safe, it was boring to me. I kept edging it to the left a little at a time (as if she was walking) and in the end, I decided to stick it right near the edge, but by manipulating the edges and directions of the strokes, I hoped it would work; or at least look intentional.
Anyway, a fun demo and a rewarding reworking experience.