I wonder if there is any way to search the forum for the hundreds, if not thousands of people who started LC, were doing well, then decided they just had to have a "cheat day/meal" because of some impending holiday or celebration, and were never heard from again.

This is not dealing with some kind of credit/debit system, like the gospel of calorie counting, which has been proven wrong anyway. You don't keep carbs low just because "less good, more bad" and make it up the next day if you slip. This is about harnessing and understanding the very complex biological system that is your body. What are the long-term issues with going off plan? Nobody can answer that for YOU. Because what is fine for one person, will completely derail another. Educating yourself (and there is no end to books, videos, podcasts, etc) as to not just what to do but why, and what exactly is going on in your body, for better or worse.

If I eat off-plan I may not gain noticeably from that particular food/meal. But I inevitably pay in one way or another, be it sacrificing mental clarity, feeling like crap physically, or just plain putting my foot on the edge of that slippery slope.