I have gobs of Polaroid film and won't run out any time soon, but even so I don't really have a "I have to save it!" mentality. If I like the shots I'm getting from it, I don't ever consider it a waste, even if it means less or none in the future. There are a couple film types that I only have a few packs of that I save for special occasions, but if I use it, I use it. I think I used up all of my 663 during one road trip to California. Wish I had some more but oh well, moving on.
Also, some film just doesn't seem to last, regardless of storage, so i need to start using it up. My 667 is getting dull and grainy. My Type 88 and 85 is all crap for the most part and I bought most of it new and have kept it in the fridge ever since. But the ID-UV and 669 that I bought 4 years ago is still like new.
Though I don't waste it like I used to when Polaroid was still being made, when I would kill an entire pack trying to get one shot.