Another huge problem with safari load/unload time is nothing to do with the ride-- but guests. There are rules for children that 90% of people choose to ignore, and then have to move around seats, people love to play musical chairs and believe it or not the biggest issue is seatbelts-- people do not know how to buckle them a lot of the times and even when they switched to different color seat belts for each seat they still get it wrong.
Because of this in the summer time when they are running max trucks, trucks can be lined up 6+ deep in the woods because the trucks cannot be sent out fast.
Also when they are running a low amount of trucks they sometimes space departures out so they can do their best to have trucks spaced out without trucks being too close or too far away.