I have a different point of view, top tier companies look for top tier candidates who are expected to be fully engaged with clients and have other planned commitments.
Being out of town on a client site is definitely a good excuse, being out of country on vacation is justifiable, however just being out of town while for example you are in Coventry and the interview is in Birmingham while you have 1+ week notice is definitely a lack of interest.
As a consultant, typically you are expected to be out of town 5 days, if traveling down for an interview is too much for you handle then you are definitely in the wrong business.
The point that I am trying to make is that out of town itself is not a good reason! Its perfectly fine to reschedule interviews, but you need to have a clear and a good reason.
P.S: Accenture pays for your expenses to travel down for an interview.