Expectations for the viva are not guarantees but they matter because they show the process at work. Expectations help because they give a platform for preparation. Vivas vary in length, but knowing roughly what to expect helps to prepare for the effort. It helps to know you can ask for breaks. Knowing how they unfold gives you a way forward.
Expectations show the big picture: candidates tend to pass, so you will too. Your viva is a test – the expectations show that too – but it’s a test that most people succeed in, and you’re unlikely to fail. Expectations are important for the viva. Ask friends, read stories and see what stands out to you. Don’t understand something? Look deeper or ask more.
Don’t expect your viva to follow an exact plan; do expect your viva to help you show the best of your work and yourself.