vulcan - // I think the problem with most interviewers is they are more interested in hearing their own voice rather than what the interviewee is saying. //
That depends on the format for interviewer and interviewee - if it's a chat show for example, there can be a tendency for grandstanding from the host, because he or she is the host.
Political interviewers are always criticised for cutting in, but as i point out when the issue is raised, they are on a short time-scale, and have a series of questions hopefully to get answered, and often the studio director is screaming into their ear-piece to move the conversation along.
For me, I almost always interview for magazines, so it doesn't matter if we wander off track, or I cut in sometimes, although I never ever say 'Yeah ...' randomly, I started off my journalistic career in radio, so that was trained out of me right from the start.
I do sometimes interview for video film, and then I am extra careful to maintain silence - if I want to encourage the interviewee to keep going, I simply catch their eye and nod, which has the desired effect but doesn't cut into the sound of what they are saying.