I had an interesting conversation with a colleague which can be summarized by "what is more important when deciding to create a new role? Interactions with others roles (ie. high cohesion) in daily business or purpose adequacy?"
Not sure how readable that sounds from the outside but to give a fictitious example: Let's say you want to create a "Blogger" role and you hesitate between putting it in the "Communication" circle which has the purpose of "spreading good vibes about the company" or within a "team" circle which has a purpose of "delighting clients in the surroundings".
Knowing the Blogger will mostly work and interact at the team level (we have many of those) my first idea would be to put it there, but at the same time the purpose is closer to the Communication circle (but with almost no interaction with the other roles of the circle)...