Okay, now it's December 27th, Christmas is done for this year. Santa delivered every present to every child on earth and to some kids on the moon. But, you know, kids of today are very picky about presents.
Assume half of the kids world wide are picky as my niece, who goes of like an air raid alarm, if only the slightest thing is wrong in her present. So, the parents have to retour the presents and get the correct one in order to silence the kid.
Santa's work is not done!
He has to organize the biggest and most efficient retour service, to exchange all faulty presents until the beginning of the of the new year.
He cannot fly another round, his licence is only valid once a year, for safety reasons, because whole air corridors were locked down to avoid collision.
How can he provide a most efficient retour system, to handle the incoming and outgoing packets?
Remember: North pole is the place to go for the presents and from there they shall be returned.
Santa's north pole base may be extended with any state of the art technology, airports, NASA style VAB... you name it and it is there