As a presenter, I silently curse institutions when I arrive to do a workshop and there is no clock on the wall. A clock is helpful to a presenter because they can keep track of where they are in their talk or session. If time slips or something changes they can modify as they go along. You can just glance whenever needed and move forwards.
If it’s viva day though, and you’re the one there to answer questions, a clock is not your friend. A clock just tells you how long you’ve been there, and whatever you see will not help your confidence. Ten minutes in, and you think, “I wonder what’s coming up?” Thirty minutes in: “Is it going well?” Ninety minutes: “How long is left?”
These are questions that you don’t need. They won’t help. At best they take your attention away from the focus for the day. At worst they knock your confidence by summoning doubts. A simple solution to a powerful problem: sit with your back to the clock or ask if it can be taken down. If you normally wear a watch, take it off. You’re fine without the time.