Running/Training plan by time or distance?

Local Paper has a weekly running blog by Bemidji, MN Reporter Steve Wagner.  Today he writes:

http://www.inforum.com/event/article/id/378013/group/Sports/

“Recently, I began reading books about triathlons, including one aimed at first-time Ironman competitors. Perhaps the most important concept transfers particularly well to running: training defined by time.
Runners are busy people with a lot of life to juggle: work, family and other commitments to start. Finding time to train can be difficult.
To aid in time management, the author concludes we should train by time – whereas most people focus on mileage.
When I began following a training plan devised by a coach a few years ago, most of the workouts were defined by time. Instead of focusing on mileage, it can be easier to just think about heading out to run for an hour. Once you accept the idea, how we spend that hour makes a difference in race performances.
Time-focused running forces us to concentrate on training principles – spending time within heart rate zones and performing specific workouts – rather than grinding out mileage.”

Interesting thought.  I have always shied away from plans that use time rather than miles.  My main reason is every race I have run has a finish based on miles and I am slow.  An hour for the average runner is about 2 less miles for me.  I felt that running for a time would leave me underprepared for a race.  

I agree that we need to focus on training specifics and avoid junk miles, but I am wondering if this concept would work for everyone?  

I do use the McMillian Running Calculators to make sure my pace for various runs is based on recent performance and my goals.  I do watch my pace times the best I can.  I also convert my miles plan to a time, so my family knows how long I will be gone and I can plan it into my schedule.  

I also wonder if this is a false dilemma.  Does planning by mileage prevent us from focusing on heart rate, pacing, etc.?  Does planning by time insure we focus on those things without simply focusing on how much time is left (“25 mins done, 35 to go. . . 26 done. . .. ).  

I really don’t know, but would love to have a dialogue on it and hear other views.  My guess, like everything else, is everyone is different and this will help some and no help others.  But I think discussing it can help us all learn something.

Your thoughts?