I think if your interview style is very Q&A oriented, or if you are burying candidates under coding challenges, you are definitely in need of some interview training. Sadly, a lot of people choose to interview this way for one reason or another.

I really dislike interviews that rely heavily on academic-type questions that delve into language obscurities. I want someone who can solve problems and explain their thought process. I'm not interested in hiring someone because of their memory for trivia. I have Google for that.

As far as coding challenges go, these can be OK, but most of the time they seem to center around weird logic problems that have very little in common with what a software engineer does day-to-day. They also put people on the spot in a stressful situation, and people will perform quite differently in this light than when they are actually working.

The best interviews I've ever attended feel like a conversation. You are sitting down with the candidate, there is a give and take, and you are talking as if the candidate is already a member of your team. You talk about problems you're facing and how you can resolve them. It's much more comfortable for the interviewee and gives you far better insight into how they'll perform on the job.