In the magical world of fiction, if torture isn't being just used to prove that the Big Bad is indeed big and bad (or that the Anti-Hero is indeed anti), it works as an instant source of 100% reliable information. The information extracted under torture is always accurate and important, even if the interrogator himself starts with no information at all and so has no way to know if the prisoner is telling the truth or lying. The possibility of having the wrong person, who will say anything under torture whether they know anything or not, will be excluded. Often as not, the victim is then released with no consequences to them if they lied.

The only times when torture doesn't work is when the tortured is just too Badass to be broken, and doesn't say anything at all. When characters object to torture, they are often portrayed as weak liberal Strawmen who "don't have what it takes" or "don't realize what's at stake". They only make moral criticisms, and never bother to point out that it's unreliable, presumably because they too know that it Always Works. Even when it doesn't work, characters who should know better assume that it will.

In Dirty Harry, San Francisco Police Department Inspector "Dirty" Harry Callahan presses down on the Scorpio killer's badly wounded leg (he was just shot with a .44 revolver) until he tells him where to find a girl he had kidnapped and left to suffocate. Naturally, he finds out where she is, only to discover that she has already died. The killer promptly walks away from the law by crying "police brutality", much to Harry's disgust.

In The Dark Knight, Batman uses it on a mob boss by dropping him from two stories up (conventional Batman interrogation techniques involve dangling the perp from twenty or thirty stories up until he talks) and breaking his legs.

LOST: The flashbacks of the Ben/Sayid torture episode, One Of Them, saw Sayid successfully torture a former superior officer of his to get the location of US soldiers. He used pliers to great effect it seemed.

Used on Buffy the Vampire Slayer - Buffy's interrogation subjects are usually demons, whose loyalties are extremely weak. Once she has someone at her mercy, it rarely takes more than a minute for them to start talking.

Played with in an early episode of Angel. Angel is tortured, and doesn't reveal what the bad guy wants. However, it's revealed afterwards that he was THIS close to do it, but the gang saved him before that point.

In his James Bond novels, Ian Fleming (who had prior experience in British intelligence) refers now and then to agents being tortured, on the implicit assumption that, indeed, anyone — even a trained agent — will eventually give up what they know given enough time and pain.