I own a WATP set, I think it goes up to three miles. I haven't done them in quite a while. In fact, I probably only did them one or two times and lost enthusiasm (that's the story of everything in my Exercise Equipment Cemetary). But the reason I bought them is that a former coworker had done them for a few months and lost 40 pounds. So I believe they probably do work.
I think I remember going almost immediately to the 2- or 3-mile ones.
Hmm, maybe you should start a WATP challenge. I'd be in.