[nonameiguess]

I actually have seen this legitimately work as well, as in being on a program where we pretty consistently hit every deadline with every planned feature at or under the promised price, for years on end.

But then take the same company, even many of the same people, and put them on a new project, and the estimates go to crap.

It really takes a lot of domain-specific experience, and I mean "domain" pretty narrowly, like knowing the code base, knowing the developers, knowing the customer, knowing the external surprises and constraints you're likely to come across because you've seen them so many times before. I've never seen it work for greenfield, even in an organization with the discipline and know how to do it correctly for their older applications they've been working on for years or decades.