On ELU, typographic usage is —well, it’s certainly not a “black-or-white” matter, but it’s too erratic to characterize as “grey”, which suggests some measure of uniformity. Perhaps »mottled« is the mot juste.
One problem is that punctuation isn’t really about language at all (Off Topic) — it’s about the presentation of language . . . except of course to the extent that it isn’t. Because even if it’s not strictly language it is semiotic : an system of arbitrary signs which convey, qualify, and (one hopes) clarify meaning. So — is it a proper topic for discussion on a forum about language? Our response here has historically been an emphatic “Sometimes”.
Another problem is that although punctuation is systematic and meaningful, there are a variety of systems and a variety of opinions about what meaning it conveys. Different disciplines (APA, MLA) and publishers enforce different rules, and for these the questioner can only be referred to the applicable General Reference. The ‘Oxford comma’ is mooted every few months around here (Exact Duplicate); the placement of commas before and after quotations is contentious (Not Constructive); and just about everybody has an idiosyncratic (perhaps we should call it idiographic, on the analogy of idiolectic) “system” of pointing. One very distinguished user here regularly edits postings to replace hyphens with em- and en-dashes (or em and en dashes) according to his own sense —endorsed, to be sure, by many eminent authorities— of what is semiotically fitting; but it appears that even he is constrained by his sensitive aesthetic sense to defy convention and surround em-dashes with spaces, because the em-dash in this site’s typeface is such a piddling, tentative little affair. Would discussion of his practice be a matter of “English Language and Usage”, or does it belong on the proposed Typography site? —Again, I fear the answer, if the question were raised, would be “Maybe”.
(And three-quarters of the users here would protest that that full stop should be moved inside the quotation marks.)
I’m afraid that no real answer can be returned to your question (which I guess makes it Not A Real Question!), and that all you can do is browse around the answers tagged “punctuation” and guess what sort of response any particular question is likely to excite —and then roll the dice.