Fear of overbooking during job interview season. How is cancelling an interview to take another interview viewed? I know someone who is finishing a postdoc in mathematics and is in the thick of the tenure-track job search.  He had something like 15 interviews at the Joint Mathematics Meetings (JMM) last week.  At the moment he has four invitations for on-campus interviews.  Of these, exactly one is one of his very top choices.  He sent me a list of seven institutions at which he had JMM interviews, has not yet received campus interviews, but would prefer them to some of the places for which he has received but not yet accepted interviews.  He is getting worried that he could book too many interviews at these less desirable places and then be boxed out of later interviews to come.  By the way, I think he is excellent and unusually broadly appealing, and I absolutely expect him to get more on-campus interviews than he now has.  I don't think I have heard of people who have actually booked so many interviews that they have no slots left, and I am tempted to tell him not to worry so much about that -- the calendar is full of days -- but I suppose it could happen in his case.  What do you think he should do, e.g. how should he respond to two on-campus invitations that are less desirable than many of the JMMs he's waiting on?  

Here is what I said so far:

1) Contact all seven desirable places, let them know the situation, and see if he can shake loose interviews from them or at least information about timing of the interviews.

2) Countenance the possibility of cancelling a job interview if he really does get booked solid.

I am not really sure about 2).  Clearly you should cancel all interviews once you've accepted a job, and cancelling interviews when you already have an offer in hand makes just as much sense.  I'm not sure about the ethics of cancelling an interview to take another interview instead.  Is this commonly done?  Would it annoy people or look shady to some?  If this is going to be viewed as dishonorable behavior even by some, I think he would really like to know that: he is as "fully honorable" as anyone I've known.
I know the hiring process in Math is a little unique. My answer is based on the assumption that an "interview" means a 1.5-2 day campus visit and that interview season is 10 weeks. Further, I assume that when contacted about interviews a candidate is typically given 3 choices of dates and that departments are interviewing about 5 candidates.

As long as you avoid campus visits on Wednesdays, you can fit two visits in a week. This means there are about 20 interview slots in a season. As the number of interviews approaches 10, the likelihood that the 3 options offered for one of these interviews will clash with previously accepted interviews. To calculate an exact probability you need to know the rate of Wednesday campus visits. At 15 it is very likely for a clash and at 20 you would have to get very lucky.

I think in this particular case the post doc is looking at 11 interviews at most and has already gotten a few rejections so likely fewer. This means that the post doc might need to tell a school that none of the dates work, but would still be able to offer 10 alternatives dates within the prime season as well as early and late visits. On the hiring committees I am familiar with providing a wide range of alternatives would not indicate disinterest. The likelihood of the availability of one of these dates depends on how busy the department is, but I would be surprised if none of them worked. If in fact there is a clash, and the school is highly desirable, then the post doc would need to cancel (or reschedule) a previously scheduled interview. Again, contacting a school to reschedule an interview is not a sign of disinterest, but rather a reality of job searches.

The real problem is not scheduling, but the ability to do a large number of interviews. The number of "slots" can be drastically reduced if the post doc has teaching requirements. Similarly, having a campus visit on Monday and Tuesday, traveling to a new city on Wednesday, and having another campus visit on Thursday and Friday is tiring. Doing that for weeks on end is the craziness of the job search. I know lots of people who have managed 10 interviews in a season with a 1 class teaching load. I don't recall anyone getting to 15.


  I'm not sure about the ethics of cancelling an interview to take another interview instead.


As I said above, I would suggest rescheduling prior to cancelling. If there really is a clash, cancelling is the only thing you can do. Cancelling the less desirable interview (after factoring in likelihood of getting a job), is the only sane thing to do. Some search committee members will complain, but no one will hold it against the post doc for long.