There are a gazillion ways to develop open source. It's more like an ethos than a methodology.

> There are books written about open source development

There are books written about different authors idealizations of how to do open source development. The fact that many people have written about different methodologies for approaching a particular challenge doesn’t make the challenge a methodology.

And, yes, I am aware that the very approach known as “the bazaar” (from the essay “The Cathedral and the Bazaar”) is sometimes referred to erroneously as “open source development”, which is a particularly glaring error since all of the examples of both “cathedral” and “bazaar” development were open source projects.

Yeah, and that does not mean those books describe how open source projects function in reality. But they should, how things are done changes.