Although I believe all the experiences are valid and work for each of you, some only make sense in specific situations. For example, if I say that I keep all my parameters with only water changes, in my opinion that can only mean one of two things. Either my corals are not growing at all (or I have very few small frags), or I am spending an absurd amount of money on water changes. The last one, is likely not even possible unless I am continuously pumping new mixed salt water in the tank because of swings (mostly ALK). Now, the reason I am saying that is because as you can se in the footnote of my post, I keep a 400gallon system that have mostly small to medium SPS colonies.
In my case I cannot not test anything. ALK needs to be tested every few days (I test daily) because my system requires me to increase dosing every 1-2 weeks. That means that my corals are going somewhat exponentially. I usually increase ALK and Ca together, but only test Ca every week. Other tests Mg, NO3, PO4 are either very stable (Mg), or I can see if their concentration is changing without testing (PO4 and NO3) with increase of algae growth. I still measure them every 1-2 weeks, but could likely keep my system without them. And this is with a continuous, 11mL/minute (1%/day) automatic water change.
So I believe, unless the size and what is kept in the system are stated, the experiences maybe misleading...