To add: the bus stops are only on one side of the street, so they have to travel in the same direction every time. The busses FROM the parks (which will become the busses TO the parks when they leave) always enter at the same gate, so the sequencing of the stops is always the same (see above).
When a bus “from” a park stops at, say Grandstand, everyone coming FROM the park staying at Grandstand gets off and everyone going TO the park staying at Grandstand gets on the same bus. Once the bus completes the loop, dropping off and picking up, it heads back to the park. There aren’t separate “to” and “from” busses.