"Orange, OH MY GOSH, you need 'Shakeallthemoneyoutofyourwallet' magic elixir from Mr. Flibynite right away or else everything will die by tomorrow!" How's that for a lie?
Since we don't really know optimal concentrations of a lot of these minor trace elements (and some are believed not to be utilized at all by corals), best rule of thumb IME is simply to assess how well the aquarium/corals are doing, and if doing well, leave well enough alone.
I had my system ICP-OES tested once just for kicks when it was doing well and I had a few 'off' parameters (per the company's opinion), but since everything was doing well I didn't change a thing. And that was 2-3 years ago...and everything is still doing well
ICP can be a great tool if something is 'off' in the aquarium and the solution can't be found using regular deduction...that's when I'd consider using it again.