So is the weed growing better now?

I do try and avoid complex methods when giving advice.
Testing adds expense, complications and a lot of explaining.

Over time and in general, folks seldom test. You are a big old lair if you have done this hobby and test religiously the entire time.

I can test for defined peroids to answer a particular question I might have.
I don't test every day of every year, there is just no need. When I do test I am careful, and very precise about it and my assumptions. I have to really stay on top of things, it's a lot of work, I must make sure that the other parameters will not influence the results of my dependent variable/s. That is a lot of work I know dang well very very few folks do this when they test.
Most simply guess on the other parameters.
They'd complain about the work a lot more otherwise!!!

Most folks tend to only test when there is an exisiting problem.
I and several folks tested a fair amount when things where going well.

I took the bold step to test before, during and after a treatment.
That gave me a great deal more knowledge than mere testing when there is an exisiting problem.

Now I know what caused that look or deficiency with higher degrees of confidence.

I test in 2,3 or 8 week time blocks (not all the time as method). I have many small tanks, this allows me lots of treatments and to redo things quick and tear down, re set up another test or treatment. Trade off is I spend little time scaping and having nice larger display tanks.
I use colorimeters or Lamotte, sometime the lab if I have multiple samples to test. I do a lot of water changes during that time. I ask specific focused questions and try to come up with treatments I think will help answer my question/s.

Then I can relax.
Now I know that NH4 causes GW, as does too many fish, disturbing older substrates, with higher light, good nutrient levels, etc.

So when I see stunted tips etc and then if I do not address that fairly quick, BBA, I know it's low CO2.

I do not need to test from here.
I also do not need to ask the hobbyists their parameters.
I already know what is going on without any prior knowledge.

And this knowledge after you have done such test is pretty much dead on every time.

The hardest part is getting folks to believe you that you are right

Later they often figure it out and then go, "dang, you were right".

Haha, that is learning process also.
And we all do it to a large degree

Regards,
Tom Barr