So I've been thinking and I think I've come up with two theories.
1. Santa is a house elf that already lives up your chimney. This explain how he knows if you're naughty or nice. Every house has its own Santa already hiding in it all year round.
2. All chimneys are linked through a temporal network that leads to a master chimney at the North Pole. This allows him to easily move from house to house and return home to refill his sack
