I really don't know exactly how I feel about "a cheat" day. I did not have one when I lost 120 lbs the first time. And, I actually did not really have one once I was at goal for 10 years. Then, one day I got tired of restricting myself so much and I started a splurge meal. I was weighing myself and monitoring things. Then, it became a splurge day and then a splurge weekend and then I stopped weighing myself. You can guess what happened. I gained back 40 or so lbs
I would have gained more if I hadn't kept some of the good habits I had learned. In January, when I started to lose weight, I did add in a "cheat meal" a few months after I started and I did continue to lose weight. I stopped once my weight loss slowed. I think its a very individual choice and it might work for someone but not for another. I personally never want to go back to maintaining while refusing to eat my own birthday cake or Thanksgiving dinner. But, I also don't want to go back to splurging and it snowballing on me and me regaining the weight. Right now, I've loosened the reigns since I'm in maintenance and I am exercising a lot. I am weighing daily still. So far I'm maintaining.