This is an interesting question in business IT. I just sat through a long meeting discussing requirements for a project that is under way. The project started without a detailed list of requirements written out.
So, the business adds a requirement that no one was aware of. I made the mistake of using the words "change request" which led to a ROUSING discussion. The business didn't want to start adding "process" when they had not been required to follow a requirements management process to date. It was a shock to use the words.
Lesson to learn: if you EVER want to control your Business IT project, don't let any progress to occur without a common agreement about the amount of control, and stick to that agreement as long as possible.
There's a layer of stomach lining I'm never getting back.