It's very wasteful - I make it a practice to discard any open packages of food (I sell unopened ones.) And it's probaby the only time of year I clean out my freezer, since it's a frostfree one.
So much *stuff*.
Resolution for after Pesach (heck, I'll start it before.) - any item of food that gets placed in the freezer (with the exceptions of ice cream and convenience foods, like knishes) will get dated and made part of an inventory list. Meat will be used within three months or discarded, and then checked off. This way I'll know what I have on hand before getting new stuff.
I have a bag full of very expensive food of unknown but probably great age. *sigh*
Should probably do the same for the fridge.