I found this interesting “marathon mistake” in an article from Active.com located at: http://www.active.com/story.cfm?story_id=13004&category=Running&num=3

Some general comments from the forumites at Runners world states that some of this is based on personal experience and not really relevant for all runners, however I did find #10 to be interesting:

If your VO2max, lactate threshold, economy, running strength, power and marathon-specific preparations are all in order, you’ll have your best-possible race. If you don’t work on each of these variables during training, you won’t have a great race. Preparing for a marathon is all about optimizing these variables; it’s not about pounding away with long runs and then hoping for the best.

This continues the theory that there is more to running a marathon than just running. Its all about how you train and prepare for it (physically and mentally).

Here is another interesting link to calculating your training pace:
http://www.mcmillanrunning.com/rununiv/mcmillanrunningcalculator.htm