I received clarification this weekend, regarding last bus out. The last departure will occur at park closing, if that particular route is scheduled on the hour and half-hour. If the normal departure on a route is scheduled at any other times, then the last bus on a route will be the first departure after park closing.
So, if a park closes at 8:00 p.m., and the route is scheduled at 7:50 p.m. and at 8:20 p.m., the 8:20 will be the last bus out from the park on that route.
So, if a park closes at 8:00 p.m., and the route is scheduled at 7:50 p.m. and at 8:20 p.m., the 8:20 will be the last bus out from the park on that route.