As far as the topic of quality verses quantity go I know that both are important in the creative process, but quantity seems to be the most important. When making thumbnails or mind maps the more I seem to make the closer I get to a better idea and outcome. Redoing each thumbnail making each one better and better you discover new possibilities. The more of something you make the better you get at the production. I think that the quality comes from the quantity. One must work up to have the quality, but first the sketches or what have you must be produced.