Water testing or no water testing?

Hey guys, as many of us already know, there isn’t just one successful way to keep corals alive and thriving despite what some people may say. What I want to know is how many of you rely on frequent water testing to know where your water parameters are to optimize your coral growth and how many of you rely on the old trust your salt mix and do weekly 10% water changes to maintain your alkalinity, calcium, magnesium and trace elements? For me it seems like over the last 17 years of evolution in the hobby, I started off keeping soft corals and leather corals primarily and could get by with zero testing and always had huge lush overgrown coral filled tanks. As time has progressed and my interests in more advanced corals has taken hold, that same type of zero testing/water change type system has consistently failed to produce good results with many stony corals, mainly sps corals to be exact. Currently I find myself needing to dose calcium and alkalinity as primary mineral supplements to get continued hard coral growth. I guess as I’ve grown as a hobbyist, the one thing that has become more of a concern to me for the original method is if your not testing and something goes wrong, what evidence or kind of records do you have to fall back on to help determine the causes for any certain problem with your corals or tank in general?