I don't think it makes a lot of sense to do it "once a week". If you feel the need to follow one specific protocol someone else has set up -no matter if it is called PaNu oder Paleo or EatWhatMakesYouHappy- then DO it. If you want to eat somehting else the then do that.
Personally I don't think know why anybody else should have the right to call me a cheater based upon what I decide to eat.
And I think that's what this community is about: Getting and sharing information and drawing YOUR OWN conclusions based upon what you know (or think you know). It does not matter what I think about your cheat day. If you want to eat that rice-laden oh-so-delicious Tekka Nigiri then go for it! You know what it does to you, to your taste buds, your well-being, your eyes, your nose and your gut.
You have the privilege, the right and the obligation to decide for yourself.