Okay this is going to sound super cheap (and not even in the good way, if that's possible).
I've decided to send out Christmas cards every other year. If I send them out every year it gets awfully pricey since almost half my mailing list is out of the country. If I send them out every 2+ years the gap is too wide and some folks will get a little miffed and delete us from their mailing lists.
Every other year is smack dab in the middle of the perfect amount. I'll save money but still stay in everyone's good graces.