If I make a big batch of blueberry buttermilk pancakes and freeze them, how long will they stay fresh for before getting freezer-burnt?
Its going to depend on the type of packaging and also the freezer.

Lightly wrapped in plastic wrap (or worse, paper) will freezer burn fairly quickly. Vacuum-sealed will last much longer.

A self-defrost freezer with wide temperature swings will burn quicker. A manual defrost chest freezer much slower.

Worst case is probably around a month or less (not really sealed, freezer with wide temperature swings), best case (vacuum sealed in stable temperature chest freezer) over a year.