AirDrop will work by passing the data from Mac to Mac so it will get the file there (although slower) if it has to jump once or twice along the way. The further away you are or the more interference, the slower it gets. If nothing else is 'sharing' the road - you get the full speed. It is like a mesh network where all the devices just talk between each other. AirDrop works outside of whatever WiFi networks are around and doesn't need a base station.
