Wow often should you have all the fittings done?

Once a year? Twice a year?

I read somewhere that you should get it done after every underwash just in case ma-wash away but it seems unlikely cause naka seal naman yung fittings.

I had it done na rin anyway right after I got an underwash the other day and asked the guy there. He said "pag mukhang wala nang laman...palitan na."

Diba naka seal nga... so how do you check?