Praying for sermons

In my observation, Christians pray different kinds of prayer for sermons.

A pastor may pray during the sermon prep phase that God will quicken and clarify his mind so that he will exegete the passage correctly, and think of suitable applications.

Before the sermon, a pastor may pray for freedom to extemporize. Even if he wrote out his sermon, he may wish to leave himself open to the inspiration of the moment. Composing a sermon in the privacy of your study is different from the dynamic of speaking before a live audience. 

In addition, both pastor and parishioners may pray that God will put the parishioners in a receptive state of mind to heed the sermon. 

Finally, the pastor may pray that his sermon will speak to the situation of his parishioners. Be especially relevant to their circumstances. In many cases he can't know what they went through that week. What challenges they may be facing. But God does. 

Now, I don't think these kinds of prayers single out any particular theological tradition. I think Christians generally pray these kinds of prayer.

However, I'd note that these kinds of prayers make far more sense in Calvinism. They assume that God is in control of our mental states. Our psychological predispositions. Hence, God can make us more receptive to the message.

They assume that God is in control of our circumstances. Hence, God can coordinate, indeed, prearrange, the sermon to dovetail with the individual situation of a particular parishioner. 

For instance, in the course of his sermon the pastor may go off message to make some unprepared remarks. As he's preaching, something crosses his mind. So he interjects an impromptu, parenthetical aside. 

After service, as the congregation is filing out of church, a parishioner may quote that part of the sermon and tell the pastor how timely that was. How that spoke directly to his situation that week. What the pastor didn't plan on saying turns out to be the most crucial thing he said.

We may take that for granted. But it only makes sense if God is providentially guiding events according to his master plan for the world.