History Main / ItOnlyWorksOnce

* In ''PowerRangersSPD'', Kat is given a special Morpher that allows her to transform, but only has one charge. She takes it and goes into battle as the Kat Ranger for the first and only time. Note that, in ''TokusouSentaiDekaranger'', Kat's counterpart, Swan, has different reasons for her Ranger form, Deka Swan, to be used. And she obviously shows up in ''KaizokuSentaiGokaiger''.

** Still musketeers and other gunmen usually carried somewhere between 8 and 16 reloads on their person (their flasks with gunpowder were known as "12 apostles", despite there not nearly always being 12 of them). On top of this, there would be carts with more powder and bullets behind the lines. While some generals really liked charging to within range, having to run through the salvos of bullets usually meant the charging formation was in worse shape than the one being attacked by the time they arrived, and stood a big chance of losing the subsequent "push of pike". So it was more common to try and destabilize the enemy formation by firing at them yourselves and by sending loose skirmishers, cavalry charges and cannon fire at them, before actually going in for the melee. So most of the time, this trope was averted. There is a reason these firearms were used. Still, a rush could succeed if performed so fast that the enemy had no time to get ready for the hand to hand. This tactic saw a short period in the limelight after the invention of the plug bayonet, which had to be plugged into the barrel of the gun, and could therefor not be mounted before going into battle.

* Many past and modern "fire and forget" Anti-Tank missiles work this way (because making them reloadable would greatly increase the weapon's weight, and the cost), giving you just one shot, so you better score a hit on your first try.
** This is also a practical matter: if you fail to obtain a first-hit kill, standing still to reload and try again will merely get you killed as the tank fires back. With only one shot, there's no reason not to leg it immediately.

* The television series ''{{V}}'' was premised on this. The red dust which was all-powerful in stopping the Visitors at the end of the ''{{V}}'' miniseries was suddenly found to be ineffective in warmer climes.

*** Ranma in the manga has demonstrated to countless opponents that any attack that landed on him once are often ineffectual later on barring PIS.The anime Ranma is far dumber and tend to fall for similar moves far more often than the manga Ranma comparatively.He actually even ask money from Nabiki. He even have decisive permanent non-cis/pis weakness that would allow Ryoga to permanently beat him base on Genma words.

* In a similar instance to the ''Manga/SaintSeiya'' example above, a ''Manga/RanmaOneHalf'' {{O|riginalVideoAnimation}}VA pitted (female) Ranma and Akane versus two powerful sisters. After getting creamed in their first match, the two leads train for a rematch. The sisters' ordinary attacks then prove ineffective against Akane (who has [[TookALevelInBadass trained up to their level]]) and their special skills are useless against Ranma (who explicitly says, "Your wind attack ain't gonna get me twice! I've seen it once and it's easier to avoid it!")

** When Cologne first struck Ranma with the [[PressurePoint Full-Body Cat Tongue]], which rendered him unable to stand even the slightest heat (and therefore locked him as a girl, since he couldn't use hot water to change back,) Doctor Tofu countered it with the Tokyo Grandpa Point --yet another PressurePoint that allows people to withstand very high temperatures. Unfortunately, it was good only for one transformation: when male Ranma was hit with cold water again, the Tokyo Grandpa Point became ineffective and the Full-Body Cat Tongue effects returned in full.

[[caption-width-right:231:A one-shot cannon that http://www.mangapanda.com/one-piece/707/3 [[spoiler: needs one hour of warming up.]]]]]]

[[caption-width-right:231:A one-shot cannon that [[http://www.mangapanda.com/one-piece/707/3 [[spoiler: needs one hour of warming up.]]]]]]

[[caption-width-right:231:A one-shot cannon that needs one hour of warming up.]]

[[caption-width-right:231:A one-shot cannon.]]

[[caption-width-right:231:Pity it only works once.]]

* The [[RomanceOfTheThreeKingdoms Eastern variant]] was [[TheStrategist Zhuge]] [[TheChessmaster Liang]], who, when faced with 60:1 odds in a battle, he sits himself on the parapet above the gate to play the lute with the gates themselves flung wide open. Due to his well-deserved reputation, the opposing general ''backs down'' rather than risk getting lured into a trap - and it fits squarely into this trope because the only reason it worked so well was due to it being the first time Liang had ever bluffed.

* [[ZigZaggingTrope Dodging around]] like an OldSchoolDogfight in ''Franchise/StarWars'', when the Empire makes a new Death Star that, when completed, will be immune to the tactics that allowed the destruction of the previous one--unfortunately, it's only half finished when the heroes get to it, and [[SubvertedTrope they simply have to repeat]] the same "single ship in a tight corridor" tactic ''inside'' the weapon to launch torpedoes into the core. [[DoubleSubversion That goes out the window]] when they find that the villains put up a force field around it. And the force field projector was heavily guarded. Sure, the Rebellion would have a shot if they destroyed the shield generator...but they weren't in very good shape. There's the indigenous population of the moon it's on, but [[RockBeatsLaser they're just Ewoks, what could they...]] [[AvertedTrope shit]].

* If your not careful bacteria can do this. If you don't get them all the first time they may become resilient to your anti-biotic so it won't work a second time.

** Lampshaded by Tony himself when Rhodey says he should have led with that: "It's a one-off."

* Tony's badass [[spoiler:wrist-lasers]] in the ''Film/IronMan'' sequel. {{Justified|Trope}} when we see [[spoiler: Tony eject a pair of smoking doohickies from his gauntlets after firing the lasers. The single shot clearly burns the doohickies out, leaving him physically unable to use the weapon again at the time. Since he doesn't grab a new pair of doohickies out of a storage compartment, we can assume that re-readying the lasers requires more than a simple doohicky swap. [[InherentlyFunnyWords Doohicky.]]]]

** This is stated by Harrington to her students at TheAcademy concerning her escape from Hades: the stunt she pulled to take out the StateSec convoy coming to retake the planet had so much that could have conceivably gone wrong, depended on the enemy being extremely sloppy in monitoring their sensors, relied on having detailed information regarding their approach that would be near-impossible to have in any other situation, and she had absolutely no other choice except to try it.

** Somewhat subverted, though, in that he still uses their programming to overload them; he purposefully miscalculates a number on his homework, and asks the nanobots to correct it. The number in question? Pi, which ''no'' computer could calculate.

* On an episode of ''WesternAnimation/TheAdventuresOfJimmyNeutronBoyGenius'', the title character builds nanobots in a flying saucer to defend him from bullies. They malfunction and begin to threaten everyone who comes within 5 feet of him. He defeats them LogicBomb style by beating himself up. Take 2: Jimmy re-hires the Nanobots as Beta Readers for his homework assignments, and they take their "correcting errors" to extremes, going so far as to start correcting human error (bad posture, fashion, etc.) He tries to LogicBomb them again by saying that flaws indicate that humans are functioning perfectly, but they stop trying to puzzle it out, call it "extreme error" and just start deleting people off the face of the earth. Somewhat subverted, though, in that he still uses their programming to overload them; he purposefully miscalculates a number on his homework, and asks the nanobots to correct it. The number in question? Pi, which ''no'' computer could calculate.

* On an episode of ''WesternAnimation/TheAdventuresOfJimmyNeutronBoyGenius'', the title character builds nanobots in a flying saucer to defend him from bullies. They malfunction and begin to threaten everyone who comes within 5 feet of him. He defeats them LogicBomb style by beating himself up. Take 2: Jimmy re-hires the Nanobots as Beta Readers for his homework assignments, and they take their "correcting errors" to extremes, going so far as to start correcting human error (bad posture, fashion, etc.) He tries to LogicBomb them again by saying that flaws indicate that humans are functioning perfectly, but they stop trying to puzzle it out, call it "extreme error" and just start deleting people off the face of the earth.