There are only 5 overarching processes in the PMBOK Guide. I've found that in common practice, 7 or more are usually defined in methodologies for software development projects (design is often inclued as a separate process, as is testing). You may create more or fewer processes in your methodology, and more is not uncommon for large projects. Smaller projects may want to define fewer.
The PMBOK Guide was meant to document best practices, but not prescribe, so there is a lot of flexibility. I think of it as a project framework, rather than a methodology. Its why it can be successfully used for projects of all sizes and in many industries.