When you study a passage, part of the study is to recognize the shape the passage was given by the author (I’ll use “shape” in this post, but could use “structure” or “flow”). There may be a logical sequencing of thoughts, or a narrative plot, or a poetic structure. One possibility is that you can take that passage shape and let it be the primary influence on the message shape.
It may be that you decide to change the shape for the sake of the message. Maybe the original recipients and your listeners differ significantly so that you have to structure the thought differently for the sake of effective communication.
However, to make such a change, in my thinking, should be a deliberate step away from the default option, which is to reflect the passage shape in the sermon shape. For example, perhaps you are preparing to preach a Psalm and notice that it has three movements each having the same shape and largely the same content. It might be tempting to “fix” such a literary “wastefulness” and use a more compact approach to preaching it. Actually, by doing so, you would lose part of the power of the passage. Our task as preachers is to communicate what a text says, but also to in some way do what a text does. What does repetition do? It reinforces, it allows truth to sink deeper, it builds on itself. Repetition with variation is a powerful tool in writing Scripture, and consequently in the preaching of Scripture.
One possibility that comes when we recognize the shape of a passage is that we will reflect that shape in our message. There may sometimes be reasons not to do this, but let this possibility be a strong one, even the default.