I would say that most people I know easily fit this heuristic, but I almost never employ it, based on the way I remember people. When I have been in a conflict with someone, I can recall a categorized list of every thing I dislike about them, and a few fights we have had quite easily, and vice versa for people I like. What this means essentially is... I have a very hard time remaining angry / happy with people, because it requires constant use of resources, and it also seems to effect my ability to remember meeting people at all. Since I store memories of other people using events instead of descriptions if I have never had a particularly eventful interaction with someone, remembering their names or any other info is almost impossible.

Occasional but rare. I have more of a problem where I have some feeling some reason and then find out I was wrong about that reason and then need to make effort to adjust my feelings to fit the data. But I generally remember the cause for my feelings. The only exception is that occasionally I'll vaguely remember that some approach to a problem doesn't work at all but won't remember why (it generally turns out that I spent a few days at some point in the past trying to use that method to solve something and got negative results showing that the method wasn't very useful.)