I see attempts here to reconcile Malmo and Daniels' notions of tempo running and I concur they are not so far apart.
JD, in the last edition of his Formula book, describes and prescribes a great many paces. The general drift is you should train at a variety of paces, or tempos. He provides tables of paces merely to help the runner find the training intensity for a given duration. I think the critical problem is that people latch onto a Daniels pace, and fight tooth and nail to stick with it because some PR indicates that this is where their VDOTs are. I've made this mistake myself.
After tinkering with a variety of methods, I found an effort based approach is better than adherence to certain pace. If I am struggling to handle any pace, or making such an effort that the next one to three days of training will be compromised/of less quality, then my training becomes inefficient. By inefficient, I mean that for a given amount of effort, I am progressing more slowly in fitness levels than I could/should.
Example: in my first two marathon build-ups, I followed a weekly long run approach, eventually building up to a 26 miler with two 20 minute surges (with most of the other long runs at least 20 miles). This, as you might expect, left me drained and flat for the following week. I was basically slogging through things and hoping for a high quality taper.
In a subsequent marathon build-up, for NYC 2006, I discarded the weekly long run thing, and pace measurement, and stuck with effort level (loosely measured by HR). So, instead of once a week, I would do once every three-four week long runs. They would be of quality - at least 20 miles, with some marathon effort surges of 20-50mins. total.
Also, I avoided Daniels type V02 max track stuff and just did tempo runs or 15-40 minutes. Even then, I would do those too hard and race them. This would leave me flat and not able to make these tempo workouts weekly happenings. That was inefficient, but at least I got the long run thing right. Also, I recognized signs of over-training that the too intense tempo work caused, and did a radical taper for NYC.
In the final 3-4 weeks before the race, I did two workouts at marathon pace (20 to 50 minutes), and nothing else but easy runs of 60 minutes max. duration. The result was a much, much more comfortable race, in a more difficult course, with a 6 minute PR.
After this experience, I've adopted an idea quite similar to what Malmo describes - run regularly at a some tempo pace (a pace that simply feels fast but sustainable and might very well be near MP) that progresses with that comfortably hard feeling until I reach home. If I can't do it regularly, then I'm at the wrong intensity level.
In fact, the two hardest things in training, I find, are: (1)getting out the door and (2)not overdoing it/getting too intense.