reply to Kimball; I don't know this any more than anyone else, but just my two cents. Programs may have different ways of sending things out:
1) like case western, with 3 interview days separated by several weeks, they seem to send out invites for each specific day;
2) some program will identify what their top candidates, and give all those people all of the interview days; some applicant will not reply, and a few days later the open spots are sent to a few other a bit lower on their list, now with more restricted days
3) there are other methods, such as rotators for one specific day and everyone else another day, and other random/seemingly undecipherable methods
bottom line to make this thread most useful: programs will have multiple recipient for their invite e-mails, and we hope to have at least one recipient post the relevant info: date, program, interview dates offered
With these information, you make your own decision. good luck.