Yes, it's like the Niels Bohr quote, "An expert is a man who has made all the mistakes which can be made, in a narrow field." You have to determine if you need

Yes, it's like the Niels Bohr quote, "An expert is a man who has made all the mistakes which can be made, in a narrow field." You have to determine if you need someone who is an expert now, or can become an expert. If you have a bunch of experts already, you can relax the requirement for new people because of knowledge transfer. (Assuming you're good about that.) But we must acknowledge the amount of time that people spend in jobs now. If it takes a year to gain mastery and people leave after 2, like you said, there's just not enough time for people to learn from scratch.