> they rewrote "20 man years of software in 4 weeks". Which is absolutely incredible

... if accurate, if bug-free (for varying reasonable values of same). Otherwise the mythical man-month seems to creep in.

That's a project that's complicated enough to require 240 developers (12 months x 20 years, fitted into 1 month), yet somehow was reliably chunked up, retrofitted into their supplier screw up, tested and deployed in 4 weeks??

I'm considering myself skeptical.