I think there are different goals, as Philosophos,suggests/implies.
That's the nice thing with a concept vs a set in stone "turn key system". I'm not trying to make money with EI never considered it even.
I do not sell advertising here either.This is solely for hobbyists, this web sites etc, everything.
I think a no brain dosing method using water changes is a simple easy to do method for aquarist, they already know the water change method.
They can stick with this is they want, slowly change a thing at a time and see and observe.
Other's might test a little here and there and modify accordingly.
Some nutty person like myself might go way off and test everything.
I'll test the min and the upper bounds.
Few test upper bounds.
Never met anyone yet except for CO2 or light.
But not for nutrients.
Never.
When looking at nutrients, there are two extremes, not just one.
This way you have an upper and lower reference to compare.
You also need excellent control, other wises there is no independence in the test or observations.
Takes lot more work, thinking and care to do this.
You also have to be willing to risk fish, shrimps, plants or algae blooms etc to test what your hypothesis is.
Most don't wanna.
So few are that interested, but it's good to know and see that some tested it, and that a few others then later tried higher/lower levels and found that they worked with similar responses.
So you can chose how much you want to do and get involved it.
Some go whole hog, others might never go beyond some basic stuff to get by.
We cannot judge others on these points, they are what they are and it's their right to be so.
We can argue which method/set of methods is/are best suited given and set of trade offs to achieve their goal/s.
Regards,
Tom Barr