There’s an old fable about a group of blind men who encounter an elephant for the first time. In the story all of them think they’ve found something different because they each touch a different part: a snake, a leaf, a tree, a spear tip and so on. All of them are wrong because they don’t appreciate the full picture.
There’s a lot of parts to the viva and a lot of perspectives that people take. Expectations, examiners, preparation, questions, confidence, your research, your thesis, emotions and more. It’s useful to zero in on one area from time to time, of course, but not to the exclusion of everything else. If you only focus on one aspect of the viva and the prep then you’ll miss something important.
Make sure you have the full picture.