I have an MD and a PhD in machine learning, and in my experience this "double PhD" intuition is completely wrong. The first and main reason is because you do no

I have an MD and a PhD in machine learning, and in my experience this "double PhD" intuition is completely wrong. The first and main reason is because you do not hold multiple roles in a company, and you are rarely able to apply your expertise in multiple domains - one domain will passively or actively be picked for you. Except maybe for some execs, who might apply their expertise at a high level. If you are in R&D, you will focus on one task. If you are a CEO, it can give you a good bird's eye view but nothing that would match a good board. And as CEO, you will not be researching, and you will need specialists in both disciplines. The second key reason why this fails is that people/colleagues/managers do not understand highly diverse skillsets. They do not let you be both. Maybe a culture shift is comming, when more people with multiple skillset will be available, maybe specific roles would be tailored for polymaths, but right now it is not the case. There are probably workplaces where it is possible, but I have never seen it done properly.