If we understand “effective” as a matter of – “Which sort of notes move you closer to shipping your ideas out?” – then I think that you have an important insight: formulating statements, advice, questions forces one to take a position, to commit to a standpoint. Already in formulating a title like that, one is putting a stake in the ground. This is even true of question-titles, because they point in the direction of next steps to be taken.
This is EXACTLY my point! 
It shapes our thinking by forcing us to articulate our ideas in narrative form and directs our thinking by providing actionable heuristics and strategies that we can use to (1) improve our existing set of ideas and (2) examine new external ideas for incorporation into our existing framework. I use the term framework here intentionally because it requires us to externalize and describe the frames (the observation schemes) we have in our minds anyway and which we would be applying subconsciously. So the note taking medium and process acts as a force for surfacing our thought processes, making them tangible and visible, and giving us a mechanism for studying and adjusting our thought processes over time.
And since our brain is a pattern-matching and heuristic-applying machine it makes sense to work towards consciously defining heuristics that benefit us rather than hoping the subconscious heuristics we apply daily are correct.
In that sense the lexically-titled concepts become the raw material we use to develop the propositionally-titled heuristics, which in turn become our “stakes in the ground” as you said, our claims that we pronounce publicly and which identify us as unique individual thinkers to others. (Whether our ideas are any good is a different matter altogether! But I posit that good note writing practices move us towards better thinking and better ideas over time.)
I think that there is still a central role for notes that are about a key concept or noun-phrase or topic
Yes I agree with this. My point was not to say that those types of notes are irrelevant but rather that I find more value in the propositional titles because those in a sense are the outputs from the note system.
This is what I meant by my statement that they give direction to the note taking process.
Many times people advise to have a “purpose” for taking notes, but many people don’t have a singular purpose so they struggle with having a directional flow in their notes.
Instead, by defining propositional-type notes as an output that helps build our framework of thinking this gives us a “reason” for note taking independent of a particular topic. This allows us to take notes without being restricted to a single topic, which in turn encourages broader systems thinking – which was exactly what Luhmann himself practiced.
I think this is a key insight into Matuschak’s system that is largely missed. Evergreen notes in his system are a distinct type of note separate from “normal” zettels / permanent notes. He alludes to this in his livestream where he writes a note capturing a term of art and description from an author and states he does not consider it to be an evergreen note since an evergreen note should be his own ideas in his own words. If you watch his livestream he in fact has a tag #e for evergreen notes, with subtags such as #e/design-systems. And he has a corresponding tag #z with some of the same subtags. I’m not aware that he defined what #z means but given the parallelism I think one safe interpretation is that these represent the bifurcation of his system into “zettels” and “evergreen notes.”
This is why I say Matuschak extended Luhmann’s system: he added a new note type with corresponding principles separate from (and improving upon) the core principles in the Luhmann-style ZK process.
So the insight I believe is this: Permanent notes can have lexical or propositional note titles, but evergreen notes are a separate type of note that seem to prefer to be written in propositional form, with some exceptions. (Matuschak has a tag #coinage for terms of art, in particular ones he coins, and these are lexical-type titles of course, as are his outline notes)
I also think that while a lexically-titled note (permanent or evergreen) can certainly begin life as a general writeup of the concept, over time as the concept is built up in the notes it will begin to become more of a hub note / outline / MOC pointing to other notes (literature notes, permanent notes, evergreen notes) on that topic.
We can make these links either lexical or propositional. I posit that a concept-oriented lexically-titled note that contains a relatively high proportion of lexically-titled links forces us to think at the time of reading. Conversely, the more propositionally-titled links that are in the concept-oriented note the more we have thought at the time of writing i.e. we have shifted our thinking leftward in the process.
(Of course we still “think” at the time we read, but the point is we shifted our thinking into establishing the framework rather than forcing us to constantly re-analyze at the same depth every time we read the note. This is why I said as a practical person I prefer developing the heuristics/strategies/claims once and then acting on them repeatedly afterward.)
This can become a signal: a note that is simply a description of a concept with few links has less “density” in our minds than one that has turned into a short description with a large outline pointing to many other notes around the same concept.
(This is usually a gradual refactoring over time, not something done immediately – I use the Note Refactor plugin a lot for this. Additionally, I find that processing a set of rough notes in a single file representing a single source gradually into individual note files using that plugin converts that source note into an outline, which acts as a signal to me that I have “thoroughly processed” that source and identified the underlying ideas in it as separate notes, vs. seeing a bunch of raw notes in that single file without many links. And that outline best captures the idea architecture from the source when it is worded as a series of propositions and conclusions rather than merely lexical terms – although I also have some def. Some term type notes for important definitions as well.)
And if we accept the distinction between permanent and evergreen notes, then an outline with a larger proportion of evergreen notes will represent a core concept with high “density” in our framework of thought. The larger the outline and higher the proportion, the more “dense” that concept is in shaping our thinking.
the cautionary advice implicit in what you write: if one wants to eventually reach the point of shipping new ideas, it is important to make the shift from seeing the associations to making commitments, in the form of notes with propositional titles
Nailed it. 
(and I completely agree w/ Matuschak’s point in that last link – there’s far too much noise from bloggers and vloggers looking for clicks in this space)
(this last part is a bit rambly but I think you will get the point)
This also goes back to Ahrens’ point in his book about the Zettelkasten process: there is no thinking without writing, and we should write with the goal of publishing because only those ideas made visible to others can become noteworthy to anyone else. And people rarely incorporate large amorphous things like system complexity or note taking into their daily thinking, but can more easily incorporate things like Complex systems should emerge from simple ones and Good note writing is a conversation involving deep thinking (actual titles in my notes) because these are claims and conclusions they can adopt. (in How to Read a Book Mortimer Adler explicitly advises to identify what I call the idea architecture of a source by watching for the arguments that wind throughout the source rather than the artificial constraints of chapters/etc, because we don’t incorporate chapters we incorporate ideas which are usually the output of arguments by the author)
I didn’t set out to convince others about my ideas; rather, I started note writing to become a better thinker. As part of that I fell in love with understanding the principles behind sound note writing and how it can shape thinking. My system currently has over 30 hub notes on a wide variety of topics with varying “density” in each.
But because of my early heavy focus on the differences and similarities between various note taking methods (I studied quite a few including some obscure ones, to varying levels of scrutiny) I identified nearly 70 principles, each a separate note, and each worded as a proposition because it shapes my thinking on the art of note writing itself. This in turn becomes a meta-practice that improves the quality of my other notes.
It also means that my opinions here and elsewhere are based on the principles I wrote about, which I sometimes pull out in discussions.
So the end result is that I “publish my ideas” through these various forums, and update my notes based on feedback as my thoughts shift on a particular idea. It’s a virtuous circle of claim / counter claim / updated claim leading to improved theories, expressed as outlines of propositions in sequence.
(Matuschak at times also at least loosely describes his outline notes as “theories”)
The fact that you are engaging with me and we are convincing each other means the propositional approach seems to be working.
Thanks for the incredibly stimulating discussion!! 