Information loss is inevitable when that information isn't used enough to become inately retained. When we focus on a particular area of study, what we learn is self-reinforcing. If I study calculus and discrete math, my understanding and retention increases in each subject, because the overlap between them connects mental pathways. If I study calculus and eastern Asian religions, retention suffers because my brain cannot make meaningful connections between the two. This lack of coherence in what I'm learning means that I'm wasting my time with one of those subjects ;)