Sometimes certain connections are extra enjoyable to send and receive from. Of course there’s nothing stopping you to keep on past the 100 for the Golden Planes-rewards but it could encourage keeping going by intemplating a tier system for more planes handled between a connection.
Perhaps every 100 handled? Or maybe next one 250, then ultimate power at… 4 or 500 - with a superspecial reward? Might need to adjust to the different connections… BRI-INN is a little bit easier than BRI-NGO