Here’s a precis (with a little bit of re-jigging of wording and order) of Jared Wilson’s helpful post.

Your sermons shouldn’t be too short, because:

• The church should subvert (and not support) today’s convenience culture
• Sunday may be the only day when some of your people get any Bible
• Hearing from God should have a prominent place in our meetings
• Scripture is worthy of sustained attention, not brief snippets
• God’s word to us is profoundly relevant and eternally important

Your sermons should be too long, because:

• Over-long sermons usually try to achieve too much
• A sermon’s aim is communion with God, not exhaustive knowledge
• People will become too fatigued to be able to listen or respond
• It is good to leave people wanting more!
• You’re not as good a preacher as you think you are!