One hour painting or "A Painting a Day" isn't a new concept. Many painters do it religiously and as a result, their work shows.  It is great practice for mixing color and problem solving quickly. For me, it's great practice not focusing on one area too long or beating the canvas to death with my brush.  I can go long periods of time without touching a paint brush and that is not good for me or any painter for that matter.  I still go days and even weeks without doing one hour paintings.  Doing daily one hour paintings are a good way to stay inspired and stay in the groove of painting.