The whole cheat notion is very much an individual thing. For starters I ask you to consider A cheat meal, not a cheat day. One meal per week where you have anything you please, if you feel you need that. Here again though reasonability should apply, you want a whopper value meal, fine go get it, you want 10 whopper value meals, you should call someone for help. For some a cheat meal works perfectly, it relieves cravings, offers psychological relief from the strict diet etc. Another thing for cravings, is that if you can allow yourself to have a little of what it is that you want without going overboard this can end the craving and prevent complete nutritional disaster. For example, craving sweets, go ahead and have a hershey's kiss or two, before you end up wolfing down a whole ice cream cake.
For me, I try to evaluate it this way, will eating this, taking this cheat meal, get me closer to my goal or not. On average every cheat meal results in an extra two days of needing to be on the diet. Think about that 8 cheat meals on a 8 week diet will add about two extra weeks to your diet. As in all things moderation is the key.