After my 60-day running streak I started to experiment with running 6 days straight, then walking on the 7th day. It worked fine, I always met my quota (~70 miles per week) without getting hurt.
The problem? It's boring as hell. And my walking day is Saturdays, which is when EVERYONE in North Virginia is out running. Suddenly I was feeling too conscious about all them running folks looking at me and wondering why I was walking when it was obvious that I could run.
So here I am, back on running 7 days a week. I'll go with what worked over the last 18 months: run 7 days a week until I feel like I need a break, and then take a REAL break day. That is no running, no long walks, just rest. We'll see how that one goes ...