I think it depends a lot on where you live;
-how much storage space you have
-what sort of construction/fabrication skills you have
-what you might need to protect or rebuild
-what you are protecting yourself from
-what the longterm function of the materials is for
If you live in a condo setting (like Canadian), you don't have much storage, but you also don't have much to do to protect yourself. Concrete walls, steel doors. Just a couple windows you might want to cover up, possibly a door you might want to barricade.
If you are protecting your house from severe weather, it depends on what type of weather. Again, part of this is all about being prepared. If the storm is coming, and you've got limited time, you will want window-coverings to be already cut and ready to go up. Bonus points if you've figured out a way to attach the coverings without significant damage to your siding and trim.
-Is it even possible to put up the coverings on your own, what about during high-winds?
-If your pieces are pre-cut and ready to go, you can go the extra step of adding a handle to make carrying/holding in place easier, and paint/treat the surface and cut edges to prevent moisture getting into the material and breaking it down over time.
-If all your windows are boarded up, and the power goes out, do you have an alternate source of lighting?
-bundle or two of shingles, or some extra sheet metal, if your roof is metal. Couple tubes of roof-sealing caulking and caulking-gun. Don't forget nails or screws.
-sheets of heavy plastic vapour barrier... clear if covering windows and want light... this can be used in many different ways, rolls take up little space, and they aren't too expensive. Don't forget the tuct-tape, and some acoustic caulking to seal it up if trying to be vapour-tight.
-what about plumbing and electrical... assuming the power is still on... do you have the tools to fix a leaky pipe (or atleast shut it off). What if the power is out for a while, and you want to hook a generator into your house to power items (with some assurance that you have to kill the mains breaker before hooking in the generator... whether it's done to 'code' or not. You MUST 'break' mains connection before you 'make' the generator connection.)
If you're preparing for 'longterm' survival, what are your skills, what do you need materials for? Personally I am learning about beekeeping and honey production. This also has the benefit of producing beeswax... heat, light, and many other uses. But, it's useless to me if, in the long term, I can't harvest the honey, keep the bees alive, or make candles to trade/sell. I need supplies to do it... more stuff to stockpile... more stuff to keep protected and ensure proper storage to prevent damage.
How 'prepared' are you trying to be? Severe weather? Social breakdown? Leaky roof on a long weekend and all the stores are closed?