As I've said: if they stay there for the likely subsequent operations (Catering, Refueling), we reduce the chance they could conflict with those other vehicles in their home position, which is always different depending on the parking size, and can even by user customized. At the airplane door, we always know where they are.
So, choose if you prefer the unrealistically man waiting, or the vehicles unrealistically clashing into each other. Sometimes, you must do a compromise, and choose the lesser of the two evils.