Do coaches and players have to be avail to media?

Does the conference mandate availability or can coaches just say no - nothing more to say to anyone right now.

(Yes I understand that as a general rule we want media access so we get info).

Just not sure how many times or ways coaches have to say they are getting back to work.

Coach may not win many press conferences as it is but it has to be tough to keep saying the same for him and the fans.