The process of doing a PhD is like doing a really hard jigsaw when you don’t have the picture to start with.
It takes time to get going. You have to find the corners, establish your boundaries, and make sure that everything fits in place.
Progress can be slow for a long time, but you start to see patterns, and slowly the gaps are filled.
When you’re done you might have ideas about what you could have done differently – but you don’t need to do them. You have what you need, and it works or you wouldn’t have the picture that you do.
The viva is telling someone about the jigsaw; they don’t have to go through the same process, but they want to know what yours was like, and what the picture was that you got at the end. Take time to think back over how you did it and what you got, so you can be clear with your examiners.
Whatever you ultimately feel about your picture, remember that your PhD jigsaw wouldn’t be finished if it wasn’t for your efforts.