I recently took a drawing/painting workshop from William Park in which we focused on painting one subject on 2 canvases for 5 days straight. I found a cluster of pods out the door which became my subject for the week. The workshop was hugely inspiring to me because Bill instructs you to let go and keep experimenting. He says you have to be able to let go of anything on the canvas, including the parts you like, to be able to paint without fear and develop the painting more. And by working on the same two canvases for 5 days, we were forced into making many changes and really rethinking the painting along the way. It was a liberating approach for me.
And a close-up: