[PaulHoule]

It depends what kind of system you are running.

NASA had two versions of the space shuttle software developed in parallel by teams at IBM and Rockwell. None of the devs had a whole space shuttle.

[serverholic]

Of course there are always exceptions. More than likely, people on here aren't thinking about NASA software.

[Rumudiez]

Which is probably why they ran it all locally first!