I removed the Avatar example about Zuko learning lightning redirection. He learned it specifically for fights against the lightning users (his sister and father) which exactly is how he ends up using it. A Chekhov's skill seems unimportant when first mentioned or trained, but surprises everyone with it's effective use later on.

{{KJMackley}}: That's much too narrow of a definition of this trope, and it is not supposed to be so similar to WaxOnWaxOff. What would the point be of learning a Judo throw if not to Judo throw someone? Even still by your definition he trained in lightning redirection specifically to counter Azula. Using it against his father was never his intention.