My interim friends have told me I have overstated the case on interim preaching, and that there are many who always write fresh material or whose rewrites are extensive enough that it's not much of a time-saver to have old material to use. I believe they're right, and apologize for overstating the case. I think it's still true, however, that the time when sermon-writing takes the most time is early in ministry in general and after a number of years in a long-term ministry. The longer you go in any pulpit the more you know you've used your best stories and examples. Moving to a new church lets you use those pieces again, even if written into new sermons. Early in ministry, in general, you have a lot of fresh examples, but are unused to the rhythm of regular preaching, which makes it harder.
So, turning to the focus of my last parts of this series, I've talked about how preaching in our religious tradition takes up a significant portion of the week, and a higher percentage for part-time ministries. It's appropriate that this big percentage of our working hours goes into the production that is Sunday morning, since this is the most visible part of ministry and Sunday morning worship is the heart of the church still. Even so, it's a lot of work for a one-time production, and it leaves less time for all those other parts of ministry which may be things that would attract the non-churched "nones," like web presence, social justice work, community building, adult religious education, and other writing and other public speaking and public presence.
There are two things we can do to change the equation. One is spend less time on Sunday worship. The other is use the worship service more.
For the first (and less radical) option, I highly recommend the workshop on "Preaching by Heart" ( http://www.preachingbyheart.org) by Rev. Stephen Shick and Rev. Dr. M'ellen Kennedy. I went through the workshop last winter. I'm a manuscript preacher and love the written word. I love writing. But I tried preaching extemporaneously from that point forward on a regular basis (less often this fall, but still using it), and the results were great. Even though I still felt like it kept me from finding the exact perfect words that I might have chosen on paper, my congregation greatly appreciated the extemporaneous preaching, something they had always liked about my predecessor, Rev. Susan Smith. And it saved a lot of time.
Shick and Kennedy argue convincingly that people today are suffering from spiritual disconnection, and the direct experience of connection more present in extemporaneous preaching is what they're longing for more than for the perfectly crafted theological argument.
Another way to change the equation by spending less time in worship preparation is through theme preaching, which is a movement that is sweeping our country. The secret to this isn't that we're preaching on themes, it's that we're doing it in groups and then the groups can share resources -- stories, images, examples, quotations. Each preacher can then frame those in their own way, but it saves a lot of research time. Essentially we're getting that lectionary benefit that Christian ministers have by working with each other and sharing themes.
There are a number of theme-based groups, I think, across our movement. But the two main ones I'm aware of are the "Soul Matters" group ( http://www.soulmatterssharingcircle.com) led by Scott Tayler (Congregational Life Director at the UUA) and the themes published by All Souls, Tulsa ( http://themebasedministry.org).
I would guess that each of these tactics can decrease worship preparation anywhere from 25-50%. For me, preaching extemporaneously probably saves me 5 hours of actual writing time, but all the other preparation time is the same, research particularly doesn't go away. Soul Matters themes, on the other hand, changed things in the opposite way -- research is decreased by maybe as much as half, but the writing time is the same. Since trying themes I've used less extemporaneous preaching, so I can't speak to how the two might work together, but it's conceivable that together they could decrease worship preparation time very significantly by decreasing both the writing and the research.
Next and final: worship and the changing church -- using the worship service MORE.