I've had the opportunity to be both the candidate and member of interview panels so I will try to capture both perspectives; please bear with me. Usually the interview process is anticipated to be around an hour long so if you finish extremely early 9/10 this means they're just trying to expedite the process because there is no interest in hiring you. Be prepared to answer behavior based questions following the S.T.A.R. method (Situation, Task, Action, Results). When answering, focus on specifically what you did in each scenario; this means even though you may have been on team that solved a problem they are trying to get you to elaborate on what YOU did specifically. Be sure to explain your answer in a manor where someone who is completely unfamiliar with the nature of the work can easily and logically follow (keep it relatively simple); DO NOT try to impress the panel by throwing out big words and proving you are a "know-it-all" in your field. For example, if you are the foremost expert in quantum physics and recently worked in NASA's particle accelerator, resist the urge to give a condensed thesis on atomic fission. Instead focus on what experiment you were performing, why you were asked to do so, what challenges and/or inefficiencies did you encounter and how did you remedy them. Lastly, there is a VERY thin line between confident and "cocky." I've seen fantastic candidates get thrown out of he running just because they were perceived as arrogant (and I mean in the most infinitesimal margin). As for follow up, because the panel (usually three members) are required to review their answers and "calibrate" their final recommendation directly after the interview this usually means they know whether or not they WANT to hire you before you even reach the parking lot depending on how many candidates are applying. I personally (although only once) seen an interview panel basically agree to extend an offer to a candidate before they even got to the elevator (or course they didn't tell the candidate this). I say that to say this; I know it's considered good practice to follow up on with a thank you/inquiry email to the interview panel but honestly this does nothing to help you. If there is an extremely close choice between multiple candidates DTE will follow up with you. My last point is there are a multitude of reasons why interviews occur (unexpected loss of personnel, restructuring, etc.). You will drive yourself mad trying to figure out why you didn't get hired. I hate to admit this (and this all comes down to who is on the panel and why the position is posted in the first place) but there's a good chance that the organization already have an idea of who they want to fill the position before candidates even apply; this happened to me. They go through the formality of holding interviews because that's what you have to do if you consider yourself an "equal opportunity" employer (otherwise you open yourself up to pretty severe legal risk). It sucks but it happens.