Definition of "reinvent the wheel" []

• To redo work unnecessarily when it has already been done satisfactorily; to rethink an already working system, technique, etc. in a needless attempt to improve it. (verb)

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• "And thus, many a prudent, penny-watching business person will decide to remain ignorant, content to reinvent the wheel rather than going to the experts."
• "Sometimes we try to reinvent the wheel when the wheel’s rolling just fine—the conventional wisdom about eating less and moving more really works!"