Some people spend far too much time in public libraries. If, for instance, you have lost your job, and you are getting funds from your unemployment insurance to cater for your basic living bills, you can end up spending too much time in a public library. At some point, it becomes clear that you are not learning anything useful, but rather, that you are wasting time. Of course, this is a radical way of seeing things, especially keeping in mind the fact that most of us are conditioned to view all time spend in a public library as time well spent, as opposed to viewing it as wasted time.
Should it become clear that you are actually wasting time in a public library, you can figure out other useful alternative uses for that time.
You can, for instance, decide to invest that time in earning money, as opposed to using it in the public library.
You can also decide to invest that time in interacting with other people and building your social skills, instead of wasting it in the public library. Actually, upon closer introspection, some people who spend too much time in the libraries come to realize that they are actually spending the time there to avoid being with people.