Why do members of the makeup or wardrobe department take pictures of the actors in costume and makeup before every take during filming?

So they can take picture and put on the instagram or any social media to promot what there doing also so the news and stuff to talk about it to

It can be for many reasons.

-Promoting the subject

-Behind the scenes

-To get hype

-Posting on media

because of the importance of consistency in data collection. but we have to evaluate the resource or information, and not just accept what is posted online since information available on the internet is not regulated for quality or accuracy.