I am glad that someone took the efforts to dig around and dispel these myths. But then even more important is the question - why we don't have enough evidence based scientific studies in the world of software?

My guess is that it is because no two software projects are alike. Differences stemming from differing technology stacks, to domains or people skills, it is practically impossible to generalize anything across them.

Unless we all standardize on a one true way of software engineering, such folklores will continue to exists and there will be a dearth in repeatable conclusions.

PS: However, I do agree with Laurent that we can work towards aggregating numbers from several real software projects than rely on unsubstantiated folklore.