Wow! Sounds like a really interesting workshop...I'm going to try the "drum machine" strategy. And I agree about contrast being necessary and effective, though sometimes it's difficult to "get out of the rut" (either rhythmic or melodic) to come up with contrast. I find that hurdle easiest to overcome when I mash together two songs (sometimes written years apart) that deal with the same idea in two different ways. Usually, one verse of one of the songs can be made into a "hookish" chorus and the other song provides the verses. Sometimes I'm able to cull a "bridge" or "middle 8" from one or the other, or even a third. I find I have certain themes I return to again and again and again and...ad nauseam, though I never seem to get sick of them. I must have a dozen "rain songs"; likewise "highway songs". I also keep a file folder for every song, and one file folder for "scraps in process". Here's hoping I get to attend a Pierce Pettis workshop someday!