I must say that teaching has given me a better understanding of some points in moral theology. I learned this stuff, but because seminary is now over four years in the past, some things were starting to fade.
I have definitely learned more about the encyclical Humanae Vitae, and how the reaction to it by a number of theologians led to an entirely new type of moral theology, which basically was a way to get around the teaching of Humanae Vitae.