Taking interview is a hectic task. Taking interview is time consuming and require constant alertness and can be monotonous if many candidates are called.
Scheduling time for an interview is really mean a lot for an interviewer. If you have given a time for an interview and you would be not present at the venue time, then its really irritating. It may hurt the egoism of the interviewer and you will be rejected definitely.
Attending an interview in schedule time is good for both the interviewer and interviewee and save the valuable time of both.