RunnersRoundTable included a link to a “brilliant” post that discusses the importance of mileage in preparing for a marathon. There, after noting the low-mileage/high-mileage (relative terms for sure) debate, it is written:
I believe the conventional high mileage training is the way to go. Not only do the additional miles increase the endurance capabilities of the athlete, but the higher mileage training is conducive to to faster speeds on the road as well. It is debatable whether this extra training increases the risk for injuries, which is a legitimate concern. As long as you run with correct form, slow down on easy/recovery runs and keep long runs at a comfortable pace, injuries shouldn’t happen which means that if you are getting them at a somewhat consistent basis, the thing to do is to find out what mechanistically and physiologically is wrong and deal with them, rather that make adjustments to running less [fewer] miles.