Consistent character roles in scenarios

I have searched on Google and Google scholar and AI and am having no luck finding actual research on the topic, so I am hoping you bright people can help me.

To me, it is common sense that you'd want to use the same character role for each character (the doctor character is always the same woman/man in every doctor-patient scenario) as it would lessen your cognitive load a bit, knowing automatically who that character is and how they generally respond, so you can focus on the actual question.

Do any of you know of research that supports this idea that character roles should be consistent? Or, if you don't agree and feel that characters should be random, do you have research for that?

Thank you in advance,

Victoria