There is the danger of over preparation, of loss of spontaneity; over rehearsal is the most terrible thing you can imagine. We do have a very close association between costume and set designer, though. And the cameraman is very important, of course. ↗
Of course as children, we all, in all cultures and societies, learn behavior from observation, imitation, and encouragement of various kinds. So by the suggestion made, we all 'pretend' most of the time. ↗
The character of Rosie is based on a woman who used to live in the same apartment building I lived in many years ago. She's taken on a life of her own, of course. ↗