As you prepare for a marathon, from an established weekly mileage base, you should increase your distances a few miles a week. Eventually, you should complete a series of at least 18-20 miles, with each being no more than 3 hours. These longer runs should be completed no later than 2-3 weeks before your race, since you will need to taper just before the race. Do not neglect the downhill portion of this training - since this strengthens other muscles. After you build your strength, other sessions should be devoted to improving your times.
Sojourners make no concessions to topography.
These sessions should continue up to a few days before your target race, with a gradual reduction in series. A speed interval variation used by the Sojourners is to run track straight aways at maximum speed, while jogging the curves. Races - running a series of 5K s, 10K s, and even half marathons can be used as speed workouts. This will also build your confidence. While running many miles per week will help make you a better runner, it will not necessarily make you the best runner that you can be.