Ted:
Yours is a really good question but to do it justice requires a lot of thought. Plus my memory works very strangely as to where I learned things.
I do very much agree with Tim Weiman though about where you really can learn about golf architecture and it's out there on the sites with the architects and supporting casts. Things happen out there sometimes differently than some on here probably think they do and sometimes for reasons that many on here are not much aware of.
And I agree with Tim on research and reading too. I hate to say it but most of what I really learned from some of those amazing educational books (particularly the text not the photos or drawings) was learned the second or third time I read them.
I learned that understanding how to do a routing (although a jigsaw puzzle with many many levels) is key to understanding golf architecture in general. That's sort of step one and then how the holes can come alive with interest and quality and particularly nuance is about the next ten steps and takes time, time and more time and that there are a number of ways to view that process--through linear formulaics, through the look of the hole, through the "shot feelings" of the hole, the hole through the eyes of any golfer, what the ball will do, what you would like it to do, what you wouldn't, what things look like, play like, not just from the tee, LZ, approach, green, but from anywhere etc, etc, and that sometimes it's all a bit Rohrsachish, unfortunately!
I can see why some dedicated single course architects, like a Crump, felt the work may never end.
I learned that really good architecture is clever and creative and sometimes adventurous and personal "note" arrangement. I learned that good architecture, sometimes is like good writing--do drafts and look to eventually edit things out until something might be lean, maybe spare but the overall essence and meaning is all there without losing an iota or an ounce of meaning or essence. In this way I learned that an excellent hole can center on one clever feature amazingly well! I learned that really enduring holes can and sometimes do go through a very complex evolution of and to acceptance and admiration.
I learned how to effecively look for options, how to test them for effectiveness, function and use and how to take holes through the "golfer level spectrum". I learned how to analyze if and how a hole is working and functioning properly by analyzing its score spectrum. I learned some of the nuances and the bottom line importance of temptation! I learned the interest and utility of deception and visual deception and that in fact some of the best holes have degrees or large degress of Rohrshachishness! I learned to identify what makes holes not work or dumbs them down. I learned what a good bunker looks like and what it takes to make it and I learned how to analyze "lines" and the importance of naturalness (on some courses). I learned the overwhelming importance of the "maintenance meld" to make architecture fire on all eight cylinders.
I haven't been doing this that long but very intensely and those who I learned things from in one way or another either viewing or talking with in chronological order with exclamations for quantity of education (my mentors so to speak) are; Shackelford!!, Coore!!!, Hanse!, Doak!(Pacific Dunes), Goalby!, and many others here and there. From at least one of them I learned to always be mindful to know what you don't know. From those not living Thomas!, Hunter!, Tillinghast!, Flynn?!, MacKenzie!(13 points), Behr!!!(!!!)--the exclamations in parentheses is when what (the rest of) this amazing man wrote finally sinks in!
I learned I personally hate ratings and rankings and also comparative architectural analysis more each day (most of what this site is all about) but that can be accepted and amelerioted by understanding that there can be my way, our way, their way, a whole bunch of different ways and I learned in the final analysis golf and its architecture really is a great big game and there is room in it for everyone....always has been and probably always will be!
What did I learn on this discussion group? As I said, probably a little of all of this or at least it's a great place to bounce thoughts off of--there are lots of shades of grey on here! There are some very talented people on here, some in specific areas only but very talented nonetheless!