Fitness seems best when we realize we need and when we need it. At first volume, imagine an axe to get to where we need to be. As we progress a file will get our skills more refined. If you can not hit your runs at least 1 minute per mile above your race pace easy needs the axe of aerobic volume. To hit your race edgs, you might need to refine with a file of speed work that tweets us to race specific intensity.