Why did that work?

The core question of "reading like a writer," or as I understand it reading to learn writing skills, is: "Why did that work?" For example: "Why did this paragraph feel so oppressive?" Or: "Why did that joke work?" Or: "How did that sentence convey mania?" Or: "How was this theme of forgotten things developed in the story?" It's important to answer. Unfortunately, it's hard work to do so. Because it's hard to answer why did that work, I often find myself avoiding that step or skipping over it without noticing.

Why skip it? Not sure! I often find that I skip over things when:

1. they appear pointless, or
2. I haven't defined a clear next step.

This isn't (1), probably. So then it's (2). That implies the next step isn't obvious to me, so maybe I need ideas to try?

I think the core thing to try is: Look at it (whatever it is) and see what's there. But that's inherently open-ended and doesn't suggest concrete steps. Maybe it is more useful to suggest prompts – things to look for, if you're not sure what might be relevant. To that end, here are some (unoriginal) prompt ideas:

1. Remember you can start writing about it before you know why it works. :) This is frequently helpful. [1, 2]
2. What words are used? Why those words? What other words – synonyms – could they have used instead? How would that change the feeling or the meaning? Similarly for phrases, idioms.
3. How's it punctuated? Are there lots of pauses or none?
4. Look at the sentence length. Long sentence(s)? Short sentence(s)?
5. Repetition? Of words, phrases? Of ideas? Of impressions/feelings? What does that feel like?
6. Any formatting choices that stand out? For example, CAPITALIZED WORDS, uNusuAllY capitalized words, smallcaps... ?
7. Can you excerpt just a part of the writing and look at the excerpt in isolation? (With the context implicit, at least, rather than seen.) This could make it less overwhelming.
8. You might have read or heard some ideas about writing; how does this connect to those ideas? A personal example: Ellen Brock's great video on describing emotion.

That's all I've got for now.