That is extreme. While fully corrosion resistant fittings are preferred there are tens of thousands of boats in service with them and are not sinking as a consequence. There is no need to change them every 5 years - that time frame is only the minimum - and it was a figure plucked out of thin air as the drafters thought they should set a minimum. The introduction of the standard did not change anything as builders were confident that their existing practice met the standard. There is no empirical evidence to support the need for changing at 5 years - indeed no evidence of what the life span would be. The only knowns are that in this application brass fittings can dezincify and extensive dezincification reduces the strength of the fittings. This can in extreme cases result in failure if the components are put under abnormal stress, for example by a heavy sideways blow.
Now there's a shaking of the hornet's nest. I've no idea. Will be interesting to know.
Apologies ianc. We took the thread off into la la land. Back on topic, I have replaced one seacock with a Tru Design in my aft heads and other than being a bit on the chunky side, is a really good seacock. The valve works smoothly I replaced the matching skin fitting too and though it was my first go at replacing, it worked with no leaks and no hassles. Leaving all the corrosion chat to one side, I think if you have space for their chunkiness they're a great road to go down.
His own mini-bio on 'BoatHowTo.com' is somewhat coy on the subject:
Thanks Dom.