Speaking of the Book of the Twelve (Hosea-Malachi) within the context of the Hebrew Bible of Law, Prophets, and Writings, Dempster reflects on their shape and function:
These covenant representatives function in the Old Testament much like the twelve apostles in the New --as emissaries and ambassadors of God's truth and as a foundation for God's house. It is not a coincidence that the number of writing prophets in the Hebrew Bible (fifteen: Jeremiah, Ezekiel, Isaiah, and the Twelve) matched the number of patriarchs and tribes (fifteen: Abraham, Isaac, Jacob, and the twelve tribes). The prophets were a mini-Israel calling back the larger nation to its covenant Lord. . . .—Stephen G. Dempster, "The Twelve," in What the Old Testament Authors Really Cared About, 298.
The inclusion of twelve prophets in one scroll ensured that they sang together, not only in physical unison but also in theological harmony. Although each of the Twelve had different parts to sing in the prophetic choir, they all followed the same Conductor, conveying his message. Furthermore, when we listen to their voices together, we hear far more than if we listen only to the individual parts.