I worked on a lot of large projects projects. Large means tens of developers and millions of lines of code and also hundreds of thousands to millions of dollars

I worked on a lot of large projects projects. Large means tens of developers and millions of lines of code and also hundreds of thousands to millions of dollars per hour if something goes terribly wrong. I just can't imagine stuff done without staging. I get that staging loosens discipline -- you will definitely put more effort if you know that nobody else is going to see it before it hits prod. But at the same time the changes we were doing were extremely complex and if we had to break it up into constant stream of small updates that each had to work perfectly we would be in a state of analysis paralysis. As expensive as the staging is, it makes development cheaper by allowing people to work in parallel and lessen the cost of their mistakes. And before somebody points out that companies do successfully deploy things without staging -- I will say that these are a bit different systems. Large scale systems tend to not be very complex -- they are just large scale. But each component of the system tends to be reasonably understandable by a single person. The systems I worked on tended to be more internal systems with less scale but had domain models consisting of up to tens of thousands of different domain objects with very complex interactions.