A ProjectVelocity metric.

The NebulousUnitOfTime metric still indicates the estimate has something to do with time.

Gummi Bears, by contrast, are sticky. They clump together. A sticky intractable problem might not take much time, but it might still wear down a team's "hit points". A given hard problem might require brief pairing between only the two most qualified, followed by everyone else reviewing their solution.
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See ActualGummiBearsForEstimation and GummiBearsConsideredHarmful.

CategoryComplexity