To be honest, this is why I became a calibrator. I had been playing with test patterns since Joe Kane Video Essential in laser disc and had moved on to DVD and BD and now UHD.
I applaud anyone wanting to learn this stuff and whilst a TV is fairly stable, lamps in projectots do change (less with age). So having both the tools and the skill set is a good thing because you can recheck everything when ever you want.
A new xrite display pro is a couple of hundred dollars. Look after it, and it will last you years. These can be referenced agsinst a spectrometer, but are very accurate out of the box.
Software like hcfr is free and easy to use.
It does take time to learn how the controls work in relation to it does to the picture. I find it both interesting and fun to do and very satisfying when I get to the end of a calibration.
As for the "secret squirrel " stuff about calibration, most of what you need has been published for years and in the end, the big arrow on the target map points the way.