Too many words.

Proverbs 10:19 KJV

[19] In the multitude of words there wanteth not sin: but he that refraineth his lips is wise.

Most sermons are way too long. They contain a lot of filler, unnecessary repetition, "rabbit trails" and long stories about the preacher. Especially considering that people's attention spans have gotten shorter and shorter. Ask church people to tell you one main point from the sermon as soon as it is over. How many can do this? On the other hand, the Lord's Prayer is four and a half verses, and everyone knows it by memory.