Your mileage may vary.
That prep tip from a friend might not help you as much as it helped them.
The regulations might say to expect X, but you experience Y.
While others get a lot of help from a mock viva, you find it makes you worry.
But while your friends are nervous, you feel confident.
While someone else got minor corrections, you get none!
And the advice you heard didn’t just make a small difference, it made the difference to your viva.
Experiences vary. Preferences matter. Not everyone will have the same needs, the same circumstances, the same viva. We can hope for minimum standards, work hard towards preferred outcomes, and still some things won’t be quite as we might like. Some experiences will be better; some tips or techniques will be very helpful for some.
My advice is to share honestly, share openly, share positively. I hope it all helps, but your mileage may vary.