I did not know this. I use ATI labs, and have had good results. I only need 'trends' mostly. If I see flouride constantly dropping, then I keep adding more per month until I see a lab result with it neutral or on the rise. That method has worked VERY well for me. No, you don't need the levels perfect, but I try to match natural seawater to the best of my abillity.I assume you are referring to ICP testing.
In general, this is a great development for the hobby. There are some though that question the validity of ICP testing. Jack Kent from Brightwell is one who seems to be very vocal about the quality of the data you will get from those who offer ICP testing.
This does remind me of hydroponics a lot. You create coral with nothing but a variety of salts and light.