… It is normal that a person has a preference for one specific type of learning and wants to spend the majority of his time on that area, such as Gemara. However, if he does not devote any time to halacho, for example, then he will not be able to observe the mitzvos properly. Similarly, my Rebbe notes that a person may learn Chumash when he is a young child and never again give it any significant time beyond speeding through Shtayim Mikra v’echad targum. The consequence of this is that a ben Torah who learns Gemara in great depth may have little more than a child’s understanding of the maasim in Chumash! Rav Kamenetsy was once in a forum encouraging avreichim to spend some time teaching unaffiliated Jews. To one avreich who was concerned about the bitul Torah involved in teaching, he answered, “And if you have to learn a little Chumash and Nachi it won’t be such a terrible thing.”
Excerpted from here.