The old rule of thumb for sermon writing is to spend one hour in preparation for each minute you are going to speak. Most Protestant churches are set up around the pulpit and the sermon. We write down lines from sermons and share them with neighbors and family. We even sometimes feel that the "point" of worship is the sermon, and everything else is there to support the sermon - the sermon is rarely thought of as supporting the music.
As a preacher, I can say that for all this work and value we place on the sermon, the shelf life of a sermon is shorter than a peeled banana. I know this. Every preacher should know this. And you know, preachers should be okay with this fact because, truth be told, we do not need a sermon.
We need sermons.
Any single sermon, even the greatest sermons of all time are still just one drop of water on the stone. One drop of water does not affect the stone very much. One drop of water is not what makes the Grand Canyon. As much as I would love for it to be, one sermon does not change the world.
Even MLK's "I have a dream" sermon, did not change the world. It may have been a tipping point or a spark, but it surely could not have done anything without the hundred of previous sermons that people like MLK, Abraham Joshua Heschel, and the nameless pulpit preachers of the day.
If we really desire to be formed by God and the Word of Christ, we do not need a sermon.
We need sermons.