The pressure to prepare a sermon is so relentless that it often robs us of the time to do some background reading and general research that would enrich our preaching. Let me make a couple of suggestions of ways to relieve the pressure and free up some time.
Of course one of the practices that many pastors follow is to schedule some spacial services and speakers. However, for most that comes infrequently enough, that we often just use the extra time to catch up on back work in other areas of ministry. When you know that Sunday when you don’t have to preach is coming, I would suggest that you use your calendar to mark out some time for some good background reading. It might be a book on preaching, theology, ethics, or some other area that provides you a deeper understanding. Another way to give yourself some breathing room is to choose every couple of weeks to deliberately re preach a sermon that is more than a couple of years old. 98% of your congregation won’t remember and the other 2 % will delight in hearing a good sermon again.
I would further suggest that you practice the “half-hour” discipline. At least three times a week, schedule yourself a half-hour to read in any of the above areas. I choose a half-hour because most of us can carve out a half-hour and you would be surprised how over time this allows you to explore some major subjects. While it doesn’t work for everyone, I discovered that I could get up an hour early and do some reading for one half-hour and some praying for another half-hour which benefited me in many ways. You could also choose a half-hour before lunch or before you leave for the day. Another possibility is to take book with you when you go to the hospital and spend an extra half-hour in the hospital chapel.
Your reading should be broader than a specific sermon. However, you can make some notes that will later contribute to some of your future themes.