My rules are very intuitive and basically based on severity of resonance. If you will.
Not necessarily of how long it resonates with me. But how strongly it does. Even if it's immediately over once the credits kick in.
Sometimes I need to wait a little for the maximum possible resonance to build up. Sometimes I need to be on my toes, so I don't forget how much I enjoyed something I decided to forget about 2 seconds ago.
If you consider movies as some sort of container for meaning (which I do), the quality of the container can also be important. So sometimes two movies can have the same score, even though contains more truth (to me), but the other has a better container, even though it's empty. So, because I'm passionate about movies, a good container means something to me as well. Some sort of meta-meaning. A more indirect connection. Movies are things I generally respond to much stronger than other works of art or media, so making movies well and making them accessible is important to me, because movies are important to me. All of that is probably close to red an green system you came up with, if I tried to spell it out. I like to do the math in my head, though. :>
I also kind of mathematically divide the rating spectrum. Into a "positive half" (50-100) and a "negative" one (I know it's not exactly half, but what are you gonna do with a 101 options...). So I basically treat it like it's -50 to 50. With 0 being in the middle and representing an average movie, a zero-sum experience. If the positive aspects weigh heavier, it may get a 13/63, in the opposite case a -13/37. I mean, I don't think of it in terms of -50 to 50, when it comes to the numbers, but on principal that's how I divide the spectrum.
0 representing the worst, exhausting, insulting movie-watching experience I've ever had (comparable to being served a turd instead of a meal suitable for human consumption), and 100 representing the most meaningful (comparable to being blown by god). In between, every positive reaction has its negative counterpart represented in numbers (1/99, 20/80, 43/57, etc...).
It may sound counter-intuitive, but to me a movie that didn't make me feel anything is better than a movie that evoked negative reactions, made me angry, upset, "you call this a movie, you impudent charlatan?", etc...which means movies that don't take any risks can get better ratings than movies that take risks and fail. But that usually only happens with movies, which do take risks and challenge conventions, but don't offer anything new instead. At least nothing that is better than the tradition/convention. I sometimes appreciate the people behind it more, and the movie's existence as well, but not the movie itself. If that makes any sense.
To put it in other words: Average movies offer an average amount of meaning, by making safe choices and doing things most people respond to with average intensity. Whereas risky, unsusccesful movies offer a lack of meaning, which is frustrating. With the frustration being proportionate to the amount lacking.
Which usually happens with movies that tackle interesting subjects, but do so in a very uninteresting fashion. Certain topics require certain attention, and certain things evoke certain expectations. So a superficial, cliché-based Hallmark movie about a pretty nanny meeting a pretty single dad is probably gonna be less frustrating to me than a superficial cliché-based movie about coping with mental illness or slavery. If all a movie has to offer is "look at how much thisandthat must have sucked!", without any nuance or detail, I don't see the point.
So, to me, boring is better than frustrating. Unless of course it's in-your-face frustratingly boring, which also happens from time to time.
But apart from that I don't have any rules written down, that I have to abide by. I trust my subconscious on that one.