Date field is fine if you want to set a definte date, for other use cases, when for example the definite year or month is irrelevant you might need another field for that.
Here are some options, I have found:
- http://drupal.org/project/timefield - provide timepicker, optional endtime and optional weekdays checkboxes (to map a time to one or manx weekdays, for eg. office-hours)
- http://drupal.org/project/interval -provides two drop downs for choosing intervals. eg "each - second day", or "each - month"
- http://drupal.org/project/cck_time - simple time field
- http://drupal.org/project/hms_field - simple time field
- http://drupal.org/project/office_hours - complex field which provide one way to store office hours