Frankly,it is the assistant directors who do most of the movie making. Be it looking into the intricacies of art direction,choreography,costumes,cinematography,dialgues,script,na rrations,briefings,follow ups,feedbacks,dubbings,fights,equipments,resources etc etc...the Director simply gets the final drafts on his/her table(though the vision and choices still remain his/hers).
Yes,the final result is the Director's brainchild,but there is more to it,between the cup and the lip...for sure!!
Those assistant directors,one day,prove their mettle by becoming prolific directors themselves...like Sanjay Leela Bhansali,Shimit Ameen,Kunal Kohli,Anurag Sinha,Anurag Kashyap,Farha Khan and even Karan Johar,who had assisted Yash Johar and Yash Chopra,before becoming a full fledged Director himself.