There are always some. For the viva think of them as exceptions to the expectations…
- …the six hour vivas, out of the ordinary, but they do happen.
- …the vivas done over video chat, which don’t happen that often, but often enough.
- …the vivas where an examiner doesn’t have a PhD, or perhaps where there are two external examiners.
- …the viva where the candidate is stood for four hours answering questions in front of a blackboard!
That last one was me. Totally unexpected, not unpleasant or terrible, just different. At the time I didn’t have either knowledge or experience to know it was out of the ordinary. I’ve never met anyone else who has stood for their whole viva.
There was a reason for why my viva happened that way: I was asked to give a presentation, and I stayed at the blackboard.
There are reasons for all of the exceptions; they don’t just happen, particular circumstances lead them that way. Not all exceptions to the rule can be seen in advance, but some – like the make-up of your examining group, or being asked to give a presentation, or doing the viva over videochat – can be. In all of those cases, there are rules and regulations for what happens.
Expectations for the exceptions.