First, the virtue of studiousness combats or counteracts a desire for knowledge which is in some way defective. A desire for knowledge may be wrong in two ways. Now, in itself, the knowledge of truth is, of course, the proper exercise of one's intellect, is an end in itself, and is a good in itself. But, our true knowledge is meant to lead us on to proper decisions of the will and to right actions. Our desire for knowledge is wrong if we omit to study that which is an obligation in favor of that which is not.
Priorities are important here.
On a wider scale, it would be wrong to omit the study of theology, philosophy, history, and English in favor of pure professional training. This is why we have a core requirement at Franciscan University. But, a second way in which the desire for knowledge may be wrong is seeking knowledge from the wrong sources, e.g., from your neighbor's answer sheet. On a wider basis here, one commentator mentions seeking knowledge from horoscopes or fortune tellers. However, it might be noted here that relying on infused knowledge from your guardian angel to get you through a history test would also be a violation of the virtue of studiousness.