The Reformer Martin Bucer wrote a little book on Scripture and preaching. In this book, he speaks about how a pastor should prioritize the material from Scripture that he’s going to preach on. Richard Muller gives a helpful summary:
Bucer not only places a priority on preaching from the Gospels, he views the interpretation of the Synoptics as a necessary prerequisite to the interpretation of John. He next assumes the priority of Romans and Galatians, but argues that simpler epistles ought to be exposited first, by way of introduction and preparation. The exposition of the Acts, he notes, must follow the presentation of the history of the gospel. Significantly, he omits mention of the non-Pauline epistles entirely. When he approaches the Old Testament, he recommends extreme caution in preaching on such texts as the Song of Songs and the visionary passages in Ezekiel and Zechariah.
Post-Reformation Reformed Dogmatics (Volume 2), 465.