@David M Having done a ton of denisometric testing, I couldn't agree more - hence my general suggestion of 1/2 box ASA and 20% less development as a starting point.
I also agree that trying to map negative density to print reflective values is mostly a fool's errand. Let us keep in mind that Ansel Adams
et al did most of their seminal work when papers were only available in graded forms. They were trying to develop technique that would best match the negative to a fixed paper grade. Hence, the emphasis on figuring out how negative density mapped to print values.
But, these days, with VC paper, the ability to split print means that the "right" density will vary locally and vary further by the soft/hard light ratio for any given area of the print. Split VC printing is an incredibly powerful tool, but it cannot print what is not there - hence my emphasis on avoiding underexposure.
There is, however, a value doing some densitometer tests - it will quickly expose a wildly out of calibration meter, thermometer, or other process outlier. But this is a "one and done" kind of thing. Having done the tests for all the film/dev combos I cared about, my densitometer sits as a nice paperweight on the shelf these days.
But to me, at least, the real value of learning to test in the early going is to create consistency of practice. We all want to just make pictures, but so many people become discouraged because they cannot consistently get onto their negatives (and thus their prints) that which they see in their heads. Testing and developing consistent technique help resolve this. I look at my very early work and then the work after I discovered testing, Zone System etc., and there is a marked improvement in my negatives' printability. Technique cannot be a substitute for vision, but vision without technique will never be fully realized.
The one area where I'd respectfully disagree is that the US "magnificent scenery" is most appropriate for these techniques while less so elsewhere. I've lived in three countries and photographed in many more. The landscape of Switzerland is every bit the equal of Montana - just different. The light in the English and Welsh countryside is astonishing and requires great facility to capture well. The flat northern illumination of Alaska can be found again in Finland. My point is that technique, well understood, brings value in all such circumstances.
Anyone who seriously studies a musical instrument knows the importance of playing your scales. They enable you to actually play music expressively later on. Densitometry, exposure control, and darkroom consistency are the "scales" of the photographer. You can make pictures without them, but you will make more- and better pictures having done so.
Happy Snaps ...