I'll chip in to say I read a dozen on-line guides to the Zone System without being able to make head nor tail of it, but when I finally read "The Negative" it all became perfectly clear. The fact that I use roll-film, and don't own a spot-meter or keep notes in the field doesn't mean I haven't found it really helpful to improving the printability of my negatives.
I'm now just in the middle of "The Print" and despite the fact that I don't use Dektol, can't obtain the papers he used and don't have a permanent darkroom, it's extremely illuminating and helpful.
For me, he writes rather gracefully, is encouraging and not remotely narrow-minded or dogmatic.
I recently also re-read Thornton's "unZone" article and it's rather a splendid adjunct to Adams.