I enjoy keeping art journals to work out compositions and just to play in for fun. During the 30 in 30 challenge I have kept an art journal next to me and cleaned my brushes off randomly on it. If I am doing line work with ink or paint or making circles with stencils I will quickly do a few on the page. I do it pretty much with no thought as to where I am placing the paint. This makes great background and starts for my future art journal pages and I am using paint on my brush that I would otherwise waste!