Chekhov's Fired Gun

Chekhov’s Gun⁠ essentially says that unnecessary details should be penalized—more directly, if a gun is introduced in Act 1, it should be fired by Act 2 or 3.

However, it is possible to, perhaps, misunderstand this narrative principle and apply it unnecessarily. I’ve seen this extensively in cheap media (most often television), where the MacGuffin gets some ridiculous backstory to “justify” it somehow. Chekhov’s Fired Gun, then, suggests the converse: once the gun has been fired, there is no need to supply its life story. A detail that has already served its narrative purpose requires no further explanation unless that explanation serves a new purpose or is engaging in and of itself.

In short:

Chekhov’s Gun: Don’t introduce a conspicuous detail unless it has a purpose (which could include deliberately subverting the expectation—sometimes called “Reverse Chekhov’s Gun”).

Chekhov’s Fired Gun: Once that purpose has been fulfilled, don’t elaborate on the detail unless the elaboration has a purpose of its own.