All I can say is don't knock it until you've tried it. I think so many people get locked into training philosophies without experiencing different training stimuli. If Daniel's says don't go over 2.5 hours on your long run, most people don't. Then, race after race, the keep hitting the wall at 2.5 hours and wonder why they can't break through it. There are so many variables going on, more than I can address in a single thread at 6 in the morning, but if I have to say anything, don't limit yourself. I ran my best marathon ever with runs in the range of 3:40 and 3:20. Much longer than the time it took me to run the marathon itself. 16-20 mile runs just don't do the same thing for me that 22+ mile runs do. They key is recovery. I am glad McMillan brought up this topic in the article. One of my favorite runners (Kenny Moore) trained this way. He had great success with limited mileage. The key, Long Runs and plenty of recovery...Here is a sample of his training prior to the 1978 NY Marathon:
Sun--Sept.25--write Bill Rodgers profile.
Mon--Easy day.
Tues--Brainstorm Eric Heiden, embellish notes,--run 6 x mile on Pre's Trail in 4:40-4:44.
Wed--Easy day and garden work.
Thurs--Easy day.
Fri--32-mile run.
Sat--Easy day.
Sun--Easy day.
Mon--6x330 on grass(last 6 45.5-46), easy 6 miles.
Tues--Easy day.
Wed--Easy day.
Thurs--6 x mile @ 4:40.
Fri--Easy day.
Sat--Easy day.
Sun--28-mile run.
Mon--Easy day.
Tues--Easy day.
Wed--3x660(1:42), 440(66), 330(48), 220(32), 110(15), jog 10 miles.
Thurs--Easy day.
Fri--Easy day.
Sat--6 x mile @4:36
Sun--Easy day, fly to Washington D.C.
Mon--15 miles easy.
Tues--Easy day.
Wed--10 mile run, 1st five at 7:00 pace and second five at 5:00 pace.
Thurs--Easy day.
Fri--Easy day.
Sat--Easy day.
Sun--New York City Marathon, 2:16:29. Ken did not run for the next 8 days but on the 27th of October won a pumpkin carving contest at Bob Newland's house.