When should thru hull fittings be replaced?

[Karafox8]

Hello folks! I need your advice. It’s seems that is time to change my seacocks. I have find in internet stainless steel cock valves and etc. which is created to be used in chemical industry. Does it good idea to use it instead bronze seacocks?
http://www.meteko-m.ru/price/zapornaya-armatura/357640/357641/

PS sorry for my English, I’m not a native speaker.

[coopec43]

When I told an experienced yachtsman that I was using a "multi season" anti-fouling he expressed concern as he said the boat should come out every year for checking.