"Knowing the right processes and tools to use is not something that should be standardised because, at least in my experience, each project is context dependent."
Could not agree more, Sam. Not to mention the fact that our industry's processes and tools are continually evolving. This is why it's the responsibility of design leaders (both IC and management) to stay current on the latest thinking in this area.
I can't think of another discipline in this space that has immutable, standardized documentation on process that can be broadly applied to any use case. The day design locks this down and sets it in stone is the day the design process completely ceases to evolve.