From Dorothy Sayers’ essay, “The Lost Tools of Learning,” regarding Latin:
“I will say at once, quite firmly, that the best grounding for education is the Latin grammar. I say this, not because Latin is traditional and medieval, but simply because even a rudimentary knowledge of Latin cuts down the labor and pains of learning almost any other subject by at least 50 percent. It is the key to vocabulary and structure of all the Romance languages and to the structure of all the Teutonic languages, as well as to the technical vocabulary of all the sciences and to the literature of the Mediterranean civilization, together with all its historical documents.”
If pressed for time, focusing on vocabulary will go a long way!