In a workshop a few weeks ago someone asked, “How can you keep the viva short?”
I took a long pause before answering. My answer: “Not much.”
You can answer questions well – providing the information or analysis requested, explaining things and so on – but that doesn’t mean that you will shorten the viva. I’ve heard stories from people who had short afternoon vivas and knew their external had a pre-booked train to catch. It’s all anecdotal though.
I missed a more important question in that session. I could have asked the person, “Why do you want to keep the viva short?” I wonder now what was at the root of their question. Vivas take as long as they take. They vary in length for a host of reasons.
There’s no need to rush: you can take the time you need to answer questions well. Many people tell me they feel their vivas took no time at all: my four hour viva went by in an eyeblink. It’s all anecdotal though!
My advice? Focus on being prepared, don’t worry about how long it will take. You can’t influence the length of the viva, but you can steer how well you will perform.