When do you need to extract the mainbody and when you don’t?

The purpose of extracting the subject is to prevent the background from interfering with the orientation, and the decision of whether to extract the subject is based on whether the relative position of the object and the background changes. If the object does not move and the person moves, there is no need to extract the subject; if the object moves (such as taking a picture on a turntable) and the person does not move, the subject needs to be extracted.