Wejo was going slower than 7-minute pace on most of his runs, and he ran 28:06. There are two schools of thought on this topic: One says "why practice running slow?" and advocates running fairly fast on your training runs. The other school of thought, to which I ascribe, says "If you're going to run fast, then run FAST, but if not, then recover--6min, 7min, 8min/mi, it's all mostly the same to your body." Many runners have had success with both philosophies. My reason for believing in taking it easy on your easy runs (besides the name) is grounded in efficiency. If you are a 31-min 10k runner, your body can run all the way up to about 5:30 mile pace without incurring any metabolic strain. So if you are going to run fast, you might as well run close to your aerobic threshold (~5:30) to get the most benefit. In contrast, no matter what is going on metabolically, the faster you run, the more mechanical stress you are incurring. So when you are just going for an easy run, you might as well take it easy because you aren't accomplishing much at 6:00 miles that isn't being accomplished at 7:00 miles, and you are increasing the risk of injury and hampering your recovery.
When you look at the training of good 10k runners, you'll find they usually exhibit ONLY TWO of the following three characteristics:
*very high mileage (110+ mpw)
*planned workouts
*a fast "easy run" pace
That is, you can have two, but not three. Two good examples of this are Malmo, who posts here often and will probably hound me for poopooing fast mileage, and Wejo. Malmo did very high milage (averaging 140 or more miles for months at a time, IIRC) at a fairly fast pace--typically sub-6:00 miles. However, he rarely did "planned" workouts.
Wejo, in contrast, also ran very high mileage (up to 150mpw) but ran very easy on his easy runs. He also typically had two planned workouts every week, typically a progression run, tempo run, or long intervals.
Because of these types of examples (for more, check out the "sub-30 10k" thread), I surmised that there is a limited amount of intensity you can do per week. You can either spread it out evenly over every day as Malmo did, or consolidate it into planned workouts like Wejo did. I have tried both, and don't get me wrong, they both work. I have simply found the latter method (slow easy runs, periodic high-end aerobic workouts) to give better results. When I get nervous and try to "force" myself into better fitness by pushing the pace on my easy runs, I usually get hurt.