Sometimes, I run everyday. I think that's what I'm going to do for a while. Short distances though. It seems easier for me to find a rhythm with running and healthy living all around, if I stick to a consistent daily schedule.
I once read an article that said that running everyday was best for your cardiovascular development. Let me see if I can find it. Ahh, there it is. There's a link to it over in the bookmark panel.
Basically, the guy's argument is that the hard-easy approach is a remnant of training programs that were developed for weight lifters. He says the best stimulus for cardiovascular development boils down to - frequency, intensity, and duration. According to that guy, people who run hard-easy, wind up running too hard on the hard days, and then are wiped out and don't get anything out of the easy days. So, he says running a consistent moderately hard distance, at a consistent moderately hard intensity, daily, is best.
I'm not proposing that anybody follow this guy's approach, although he was a coach and his team won some crap, but I guess there are plenty of coaches that follow a hard-easy approach and they win crap too, so I guess you should just do whatever you want to do and you can find a coach to tell you to do exactly that. In fact, let that be my advice for runners : Do whatever you want to do.