According to Coughlin, "The job interview process isn't about convincing someone to hire you -- not until the final stage, anyway -- it is about convincing each individual along the process to approve you to advance to the next stage." Plenty of people you encounter within your next prospective company may have no strong opinion one way or another about your candidacy -- unless you make a negative impression. As we often say, make sure to treat everyone in the neighborhood of the interview as if they can veto your job search; there's a decent chance they can.
Furthermore, bear in mind that the interview process is likely to go into second, third or more rounds. As Darryl Taft reports in "What to Expect on a Second and Third Interview," HR professionals find most job seekers far better prepared for the first interview than for follow-ups.
Look at it this way: The first interview is intended strictly to winnow candidates who may have looked good on paper (or in pixels) when the recruiter scanned their resumes but aren't as compelling in real time.
The second interview is where you're likely to be asked for specific examples where you fulfilled the promise in your resume. "Think of it as layers of a cake," said Marilyn Monarch, group director for HR consulting and services at Citrix Systems. "We're trying to find out the applicant's work history for the last five to seven years -- If we're talking a second interview we've got a solid candidate. They've moved beyond being a suspect to a prospect."