When the cast of an audiovisual work includes a bard, or another type of professional musician or singer, but they only seem to perform a single song in the course of the story, instead of numerous, as you would expect from a seasoned performer.
There can be a number of in-story justifications for this, but out-of-universe, it usually boils down to the production costs of writing and recording a plot-relevant song specifically for the story.
Compare One-Hit Wonder.
- Brook from One Piece only ever plays "Bink's Sake" until the Time Skip, even when he asks for requests.
- A variant occurs in the anime adaptation of Genshiken, where Kosaka is very skilled at playing video games, but aside from a VS match of Puyo Puyo (which mostly happens off-screen) the only game he's ever shown playing is Guilty Gear Isuka, and only the exact same Sol vs. Jam match every time.
- Pretty Guardian Sailor Moon features Minako's idol singer career as a major plot point, but viewers are going to have to hear a lot of repeats of "C'est la vie".
- Lost has the rock musician Charlie, whose band Drive Shaft seems to have one and only song, "You All Everybody". After mockery from fans, it was later revealed that the group were a One-Hit Wonder.
- Uncle Jesse on Full House. When he wasn't being an Elvis impersonator, his only real hit song was "Forever." Stephanie continues the tradition on Fuller House with "The Boy Next Door."
- The Zit Remedy (later the Zits) on Degrassi Junior High and Degrassi High only had the one song, "Everybody Wants Something".
- Iolo FitzOwen from the Ultima series may well be the king of this trope: despite being present as a famed bard in every installment (except VIII), he is only ever credited with a single full song, "Stones", which he didn't even compose until Ultima V (and whose lyrics were actually written by his wife)!
- Leliana in Dragon Age: Origins prides herself in her bardic past (although bards in this series are not just performers, but also assassins and saboteurs for hire), but only ever sings once in the course of the story, namely "In Uthenera", an ancient elven funeral song. Later games don't see her sing at all, although she does perform the same song at Wynne's funeral in Asunder.
- Lohse in Divinity: Original Sin II is a world-famous bard and several NPCs recognize her as such, but she only ever sings one song in the game, "Sing To Me". This is justified by the fact that a powerful demon that is possessing her hates music on principle: the first time she tries to sing in the story, he makes her break her lute, and she doesn't sing for the second and final time in the game until after he has been exorcised from her shortly before the final act.
- Azura from Fire Emblem Fates is a Songstress, but she only ever really sings one song, "Lost in Thoughts All Alone". This is justified in-story by it being a versatile Magic Music, which she can use to achieve different magical effects, focused on buffing allies and debuffing enemies. Thus, Azura simply doesn't ever need to learn any other songs.
- Averted in Saints Row, where Aisha's fame in-universe matches her actual presence on the radio, with no less than three singles playing on different in-universe stations during regular gameplay. It's particularly notable because Aisha is just a minor side character in the Vice Kings story arc, yet Volition hired an professional R&B singer-songwriter to voice her and to record all three songs exclusively for the game.
- Jimmy (The Bard) in South Park: The Stick of Truth only has one real song: The Maiden from Stonebury Hollow.
- The New Scooby-Doo Movies: In the episode where Jerry Reed guest-stars, he sings a song to help the gang find him. Instead of singing any other songs he might be known for, he sings "Pretty Mary Sunlight" over and over.
- Parodied in Family Guy's Shot-for-Shot Remake of A New Hope, Blue Harvest, where the leader of the Cantina Band subtly implies that they only know one song.
Bandleader: Thank you, we're the Cantina Band! If you have any requests, just shout 'em out! (aside, in a high voice) "Play that same song!" (normally) Okay, same song! Here we go! (plays the first song again)