Less running could very well lead to faster racing for a college student who is running 100 miles a week and trying to get straight A’s as a pre-med student. This human is stretched very thin and running 80 or even 70 miles a week could lead to faster racing for him/her. But this person is the exception to the rule. For the average runner, running more will lead to faster running. End of story.
If you want to run faster, you need to run, and you may need to run more. This is not a hard concept to understand when we apply it to other endeavors. If you want to learn a language, you need to speak it; if you want to become a better cook, you spend more time in the kitchen; if you want to become better at playing the guitar, you play the guitar.
I love that magazines like Runner’s World (RW) get novice runners excited about the sport, helping them to finish their first race with a minimal amount of training. But when the novice runner wants to make the jump to running PRs at a variety of distances, they’ll need to ditch RW and pick up Running Times (RT), which will honestly discuss the fact that more running leads to faster running 90% of the time.
Obviously there are caveats to the idea that running more leads to running faster. If you try to crush every workout while simultaneously running your easy days too hard during a phase when you’re increasing your mileage, then you’re going to get hurt. You need to slowly build your mileage and you need to do so with a training plan that has workouts that are incrementally more challenging. That’s the way to improve as a runner – run a little more, run a little longer on your long run, and incrementally do workouts that are more challenging.
The bottom line is that for most runners, running faster isn’t going to happen by running less.