Should you take a rest day?

I take one day off each week, and a day off means just that, a complete day off. Interesting that 2 of the best runners, Sammy Wanjiru and Paula Radcliffe take a rest day each week, or every 8 days for Paula. Additionally, many elite Kenyans don't run on Sunday for religious reasons but nevertheless, it's a complete rest day.

http://www.scienceofrunning.com/2010/04/there-is-time-to-rest-not-halfway-rest.html

Harry