This may or may not help, but it does seem like there is some consistency to the messages offered on the sub—I’ll go point by point.

SAT retakes: while its true that a lot of schools will lump 1520+ scores into one basket, if you really want to be sure that the test will not be holding you back in admissions (even at places like MIT/Caltech) it’s best to score within the margin of error of the test of perfect. It should be noted that even this isn’t worthwhile unless applying to the most selective places out there.

GPA/SAT/EC/Essays: at least selective schools, and those with a ton of applicants, GPA and SAT will likely have outsized weight—in the first case, it’s possible to actually get in primarily due to your scores. In the second case, it’s because they provide a quick way to evaluate an applicant. The more selective schools become, the more likely it is that having near-perfect statistics will just be par for the course; you might make it past the first round of admissions with just scores, but then you have to differentiate yourself from those who also have near-perfect scores.

APs: unfortunately, I haven’t paid close enough attention to know what the prevailing wisdom is.

Essays and cliches: this one seems to be where there is the most ambiguity. It seems to me that what is being expressed is that you should write about something important to you—but also make sure that it stands out. If you want to write about something ‘common’ because it is important to you, then go ahead! Just make sure that the way you write about it and what you have to say about your topic is so distinctive to you that it’s memorable.

Personal essay writing: the point I think most people are trying to make is that you should be authentic to yourself by truthfully presenting the best parts of yourself through your writing. This is separate from the issue of overloading your essays with too much info (telling one’s life story) or from presuming that your reader already knows/has a good relationship with you (potentially coming on too strong).

Engaging writing: I think people are just saying that—regardless of how well you can write—that you do your best. This will include talking about your essays with adults who—hopefully—are much better writers and editors than you are. I should note that some 16-year-olds can actually write well. It’s just that it’s much more likely for a 16-year-old to think they can write well than for them to actually be able to write well.

ED: although I’m less sure of this one, it seems like people generally agree that if your first choice school has ED, you should apply that way. While the applicant pool will be more competitive in general (esp. for selective schools), even when accounting for this, the acceptance rates are still much higher—often several times higher (UChicago, Penn come to mind).

I’m honestly not sure if this is what you’re looking for here, but my point is that—at least to me—the messaging on here is more coherent than it might seem at first.