There are statistics about the viva, both in terms of experiences – around 50% of vivas are two hours or less – and outcomes – around 85% of candidates get minor corrections – but these are only useful in terms of sharing broad expectations. Don’t just use the numbers to imagine a most likely scenario.
Instead, put them all together to create a smudgy, blurry image. Don’t just hope that your viva is less than two hours but work so that you feel confident whatever the length. Don’t just believe your thesis will pass with minor corrections whatever happens, work to make it the best possible thesis it can be.
Stats help tell the story, but it’s not enough to just hope for a particular outcome or experience.