Malmo,
I don't mean to put words in your mouth but I believe you have considered the long run to be one of the more unnecessary parts of training, though you have not labeled it worthless by any means.
As I understand it, though I am far from a physiology buff, the long run enables your body to create more blood cells to carry more oxygen so it is enhancing your body's storage so to speak. Without a long run, how is this accomplished? I would like to know that I have something extra in the tank thanks to a long run.
Lastly, this long run being 30% of your weekly mileage at most, that pretty much makes all beginner marathon programs fit for a trash bin right? They top out at like 30-35 miles a week and the longest run is usually like 20 miles.
Thanks in advance.