One of the way artists work is to draw out quick thumbnails of the panels they are going to draw before they commit to the full size page. This makes it easy to fix things before they find out it doesn't work. Artist Steve Lieber has a page here with that has four pages of thumbnails on it. This is for a boxing ad for a client. One of the cool things about hanging out the the guys at Periscope was to see how they get some of their daily work done.