This is a thread to discuss all games and all one-time-use items in them, how you feel about them, when you choose to use them, why, and so forth.
Let me start by giving an example: Borderlands 2 has one-time-use keys which unlock chests for great loot. Once you use it, its gone forever, and this is across all your characters. Knowing that it was a one-time-use item, I saved the key through multiple characters never using it. Eventually I got bored with Borderlands 2, and only then did I bother to use the key. This happens to me in most games: I stick onto a one-time-use item for way past normal sense, never wanting to use it. Same goes for limited consumables in for example Fallout 3, New Vegas, Oblivion and Skyrim. I have this great scroll of epic power, but I don't want to waste it. I have this stealth-boy, but I don't want to use it. Etc. Even poisons which cost more than 10 in oblivion and skyrim would never be used by me, simply because I didn't want to waste them.
I'd like to hear how you feel about one-time (or limited) items in games. Are you like me, cling on to them for 100 hours with a single character, get bored with it and restart the game with a fresh character, never using that stealth boy you found? Or do you perhaps think you'll always find more, in which case the first question is more relevant to you: How do you use one-time-use items?