I heard "if it ain't broke don't fix it" from my Dad starting about age 12. He was a mechanic and that was his frame of mind: cars either worked or were broke, and if they were broke you put them back the way the manufacturer built them. He sent me off to engineering school, where we learned that the people who designed things were constantly innovating and making tradeoffs trying to make things work better, because their competitors were doing the same thing.
It's not obvious to me that everyone who didn't win would leave on Saturday morning. Many attendees would have already made travel plans, bought banquet tickets, raffle tickets, tour tickets, have non-refundable hotel reservations, be waiting for the vendor clearance-sale, or want to take one more circuit through the contest room. A modeler with vendor-money left in their wallet isn't about to leave. As long as there is stuff to do on Saturday afternoon there is no real reason to pack up early. There would be a tendency for non-winners to start packing up around 3-4:00 PM Saturday afternoon to beat the rush, but you could minimize that by having some "big event" about that time: a big name seminar or a pre-awards happy hour that was already included in the price of registration, so that people would want to stay for what they had already paid for.
I'll be the first to admit trying this would be an experiment; we wouldn't know if it would work or not. That is the nature of innovation: you study it as well as you can and make contingency plans, but in the end you don't know if it works until you flip the switch and see what happens.