This is not really the final word in the sense that there are no more words to be spoken. It's the final word in showing that point estimates are fundamentally useless. The quest to produce a credible estimate for a project's cost and schedule is not solved by serializing with work effort. It is produced by constructing a credible Cost Estimating Relationship (CER) model.
Here's an example taken from training materials in the domain where such things are used everyday.
It speaks for itself...
