Wife no1 was a bit like thatModern refrigerators and freezers are frost-free. You never have to defrost a refrigerator, only a freezer if it's not frost-free. If there is a frost buildup on the walls and shelves of your freezer that's more than 1/4" thick, you should defrost.
We have an old stand-up freezer. I defrost it once a year... or when I can't get something out because there's either a stalactite in the way or it's frozen to the shelf.