The first 90% of the code accounts for the first 90% of the time; the remaining 10% takes the other 90%.
Cargill's rule from Bell Labs. The 180% is the joke and the observation is exact: integration, edge cases and deployment consume time that the feature-complete estimate never included.
In practice
- A release that is feature-complete in six weeks takes another six on integration, edge cases and deployment.
- A kitchen extension that is "basically done" takes as long again for the snagging list nobody scoped.
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