Tim Keller – 14-16 hours.
John Piper – All day Friday, half day Saturday.
.Matt Chandler – All day Tuesday, all day Thursday.
Kent Hughes – 20 hours.
John MacArthur – 32 hours.
Mark Dever – 30 to 35 hours.
Mark Driscoll – 1 to 2 hours.
By God’s grace my memory is very unusual. I can still remember a section of a book I read 20 years ago while preaching and roll with it. I’ve also never sat down to memorize a Bible verse. Yet, many just stick, and I can pull them up from memory as I go. Lastly, I’m a verbal processor. I think out loud, which is what preaching is for me. A degree in speech and over 10,000 hours of preaching experience also helps. And most importantly and thankfully, the Holy Spirit always helps.
When I get up to preach, the jokes, illustrations, cross-references, and closing happen extemporaneously.