Stringreen, Fact is, if one is going to be truly anal about maximizing the listening experience for each and every LP, then one would be constantly fiddling with tonearm parameters. Maybe I should be embarrassed to admit it, but when I am in a listening session, I want only to get lost in the music. I do take pains to set up, when I first mount a cartridge in a tonearm, but after that I rarely change settings except perhaps to fiddle with VTF once in a while, by a few tenths of a gram up or down.
I will never forget the first time I heard a Triplanar that was set up for azimuth. At that point in time (must have been the 1980s), no one was talking about "azimuth" at all. There were nearly no tonearms or even headshells that permitted azimuth adjustment. Herb Papier himself, the inventor and for many years the maker of all Triplanars, was doing the demonstration. It was striking how the sound stage, imaging, whatever you want to call it, "locked in" (to use your words, which are very apt), when Herb set the azimuth correctly. At that moment, I knew that I had to have a Triplanar, but I had to wait several more years until I could afford it. I guess I have become lazy. However, I still have the Triplanar, a Reed, and several headshells that permit azimuth adjustment.