One suggestion to working faster and looser is to on start multiple paintings at one time. I use the same paper size and color palette to work up four different versions. That way, I can just move from painting to painting, adding a little here and there, letting it evolve more naturally. Everything is a little less important or precious so I don’t get as frustrated when a painting isn’t working out. I just move on to the next one and come back later with a fresh perspective.