[Retric]

People use different aspects of their education and it’s vastly faster to pick something up the second time. So you may have never used a given lesson, but other people in your class may have found it really helpful.

Sometimes going a few steps deeper helps you retain some useful bit of info. I ended up making useful of various bits of chemistry decades after taking the class, but understanding the basics was still helpful.

Finally basing things on utility is just a prediction. Some things that seemed useful turn out less so as technology filled in a gap.