I think the Wendie Plan is designed for long term thing to be honest. But youll probably find it stops being so effective anyway. My understanding of it is its more to kick start your metabolism. If you were to do it for a while it would be counter productive. WW dont recommend doing kick start for more than a couple of weeks, Id think the Wendie Plan would work on the same premise.
If the up and down element suits you maybe its worth looking at JUDDD
I was looking back at my diet 'diaries' and I did the Wendie plan for 4 weeks. I had a 7 week sts, wendie'd for 4. The first wendie week I lost 5lbs, then 2lbs, then 1lb and 1lb. I then went back to normal pointing. Don't know why. I didn't go into detail
Personally, I don't feel it's right for long term. There is a temptation to eat unhealthy foods on the higher days, and after a while, struggle on the lower days. I do think that it would still work weightwise, but I think it's tempting to use rather than give the normal WW plan a really good try.
Personally, I feel that the Wendie plan is an ideal tool to use when you have long plateaus (a plateau being about 4 weeks+) of stay the same, and then only use it to get you over that.
Oh and BTW. Juddd is much more extreme.
WW is a good diet if you follow it to the letter and chose good foods that will help keep hunger at bay and teach your body healthy eating habits. Trust it