You can eat them all day long, but if that is your only food, you will starve to death. So much of what passes for preaching today is a lot like doughnut holes. I once asked a pastor if he preached topical sermons or expository sermons. Before I reveal his answer, consider two definitions. Topical sermons are just like the name suggests, you choose a topic, find a few scripture verses dealing with that subject and build a sermon.
Expository sermons expose the meaning of a passage of scripture.
To preach an expository sermon, a minister must first learn what the passage meant to its original audience, then he must relate it to the lives of his listeners. To preach a topical sermon only requires a concordance. Topical sermons can be good sermons. Like all roads which led to Rome, all of his texts led to water baptism. The next Sunday, the good reverend was back in the pulpit and by way of introduction, he repeated the meeting with his deacons.