The problem with over testing, experience, and intuition. Designing something is about making a choice. Right or wrong.
Why I don't think you need more evidence before getting started. It's about a learning mindset.
I tell people to kill their personas because of my own experience of researching and designing them.
This is something that many teams struggle with. These 5 questions will get you started.
Why user research needs to start by looking for the most significant problems. Are we even building the right thing?