How often should you change a riding hat if it hasn't been damaged or dropped?

[Follychoppins]

My "old" gpa I used to wear in the rain has "disappeared" from the back of the car. ( No idea lol) It was dated 2001. This got me thinking.....it wasn't damaged, it hadn't been dropped but it was nearly 10 years old so probably ready for the bin anyway! I have bought a new one which means my next oldest will become my bad weather hat but can anyone give some proper advice on this please? Thanks

 

[Sparkles]

No idea!

I still have one of mine from about 8 years ago....so not qualified to talk!

 

[royal]

Every 3 to 4 years as the polystyrene in the hat degrades and that is what protects your head!