A typical day is at least 12 hours, but it could be longer. If you agree to be an extra, your presence is needed all day long.  If you are scheduled to work multiple days, you must work all of them. Otherwise, the scenes won’t match up.  If you can’t commit to the whole day each and every day you are scheduled, let the casting company know before your first day of shooting. While working as an extra, you should enjoy your experience on set. However, the job requires your hard work and cooperation.