Some things are worth repeating, that they might not be forgotten. The book of Proverbs uses repetition to teach us the importance of correction and hungering after wisdom, the danger of legalism, the value of Christian friendship, the need for sexual purity, and the reality of eternal life.
Discipline and correction is important for society and in the church, but is frowned upon in our post-modern society which values tolerance. The author of this article describes when and how to rebuke others.
"I urge you, Timothy, as we live in the sight of God and of Christ Jesus (whose coming in power will judge the living and the dead), to preach the Word of God. Never lose your sense of urgency, in season or out of season.