If they don't, the problem is with the homilies. One of my favorite pastors has a practice of introducing scripture readings with some context when required. Greatly enhances what one understands from the reading. 

Actually, upon reflection, there can be two problems with understanding the diet of scripture we receive during the Liturgy of the Word. The first is the quality of the proclamation. The Jesuit pastor mentioned in my first para, had a fetish about proper proclamation, so we always had highly trained Lectors. Visiting about, however, I realized to my surprise this is no always the case.