However, when the "101" answer does turn out to be the right one, it is a nice shorthand to be able to say "remember your XYZ 101"---i.e. not everything is an e

However, when the "101" answer does turn out to be the right one, it is a nice shorthand to be able to say "remember your XYZ 101"---i.e. not everything is an exception. In this sense it's related to the saying "don't miss the forest for the trees."