Another article for Permabanned, and anyone who believes high weekly miles leads to injury:
http://www.runnersworld.com/sweat-science/does-overuse-really-cause-injuries
http://www.runnersworld.com/sweat-science/does-overuse-really-cause-injuries

I'm sure, as with most things in life, the best balance lies somewhere in between "all intervals all the time" and "no intervals ever".