I agree that smaller projects make sense. Also, I have had students simply add blending to their cities, and they turned out pretty well. Blending with pencil seems to take less time than colored pencil (maybe because we practice blending a lot in the beginning). Deadlines have also helped my students stay focused. I'm not sure how I feel about many projects going on at once. I can see how some students would thrive, but others would be confused (I feel especially special education students). Maybe if you would have one large project going on, and a mini project that they could use to "take a break" while still covering curriculum....just a thought.