Ody, actual mileage may vary considerably on that. There really aren't any non-local rules requiring interviews at all in DOD, and I've rarely seen them used for anything besides picking the final winner from the 'Best qualified' list, never to winnow the complete referral list down to the 3-6 'Best qualified.' It's pretty discretionary with the selecting official, and just how afraid that person is of making decisions they might have to actually explain later. The main function of panels and interviews is just ass-coverage, in my civil service time I was hired just off my resume and references twice, and by an interview process once (And defended quite a lot of other selection decisions in EEO cases over the years in all three jobs).
No argument. It all depends on the supervisor, I guess.