Yes! We had a 730 BoG reservation for a 7pm MK closing in early January. When you're heading towards the buses, several security guards and other cast members are there. They ask where you're heading and if a bus isn't lined up for your specific resort, they'll pick an empty one and tell you to head to it, you tell the driver and then off you go on your own personal bus!
Ok, it may not always be empty, but that's how it was for us.