What's the point of validation flights before airshows?

Aircraft at Farnborough are performing validation flights this week.
What’s the point?
If the validation flight is on a bad weather day does that mean only a bad weather display can be flown.
What’s the purpose of The Red Arrows doing a validation flight (as they did yesterday). Surely they know what to do already?
Accidents at air shows are caused by mistakes, unexpected events. So would the validation display prove anything for safety?

Just wondering.