That's a common misconception. Magnetic north declination from geographic north increases to its maximum as one approaches the geographic north pole (by definition). Yes, technically, your geographic time may reverse by years, but the increase in magnetic time, being equal and opposite, will effectively cancel out that effect.

This is far too technical. Are you one of those "scientists" I hear about? :)

Some say that if you go to the international date line and climb over the map's edge, you'll find the secret fifth Carmel Tunnel that will take you straight to Big Math HQ. They won't let you go there easily.