As the person has subsequent experiences that do not fit the generalization, they become indexed under it as exceptions. This rich indexing helps the student get reminded of the relevant generalization, and to go beyond it when it fails. Schools, though, tend to present generalizations before specifics. But a generalization is really only valuable if you make it yourself. The reason for this is simple enough.
Generalizations come from cases, lots of cases.
The generalizations we remember we make ourselves, drawing on the rich case base we have acquired that has, in a sense, forced us to make that generalization as a way of tying together what we know in a useful form. When we make such a generalization ourselves we can be sure to remember it because we obviously needed it. We needed it because the same kind of cases kept coming up and we needed to understand them. Generalization and understanding are intimately connected. Generalizations that we are told have no place to sit in memory, no cases they tie together, are quickly forgotten from lack of use.