Ummmmm, Wellllll, not to throw gas on the fire but we can over-complicate things at times. Please understand I am not defending the way he does things. Sometimes we test too often and then throw chemicals at it thinking we have the right answers. A better measure is to not be in a hurry, let things stabilize and show itself to be stable and then add fish slowly knowing that in spite of all our best efforts there will be another adjustment peroid to go through again.
I don't own a test kit either. I have my eyes and my nose to tell me when something is amiss. I tried the test kit routine and all I did was kill fish with trying to micromanage my water. I threw out the test kit and my fish quit dying. I guess it stressed the fish too much to stuff them in a tiny test tube! LOL - NO J/K!!! Back on subject - No, I do not test my water. I do water changes on a regular schedule and sometimes will do an extra one if I smell fishy water in one. By the same token, I spend more hours in one day with my tanks than some people have available all week for them. With the amount of time spend I usually will notice anything out of the ordinary very quickly.
What your brother does isn't far off from what we did 30 years ago or so. No, it doesn't make it right and we were lucky back then too.