Preface: I graduated from one of the top public high schools in Arizona and will be starting classes at Stanford in just a few weeks.

It's been my experience that the overwhelming majority of AP / honors students (the top performers at a US high school) are more preoccupied with the signaling effects of any given activity than its immediate or long-term effects on human capital growth. In the AP classes in which I was involved, I'd estimate 50–75% of the students enrolled in the class not based on genuine interest but rather driven by the will to "be an AP student" or "have a good-looking transcript." Even the majority of administrators and counselors focused on the signaling side of the equation, advising us to build rigorous schedules that "demonstrated" our academic persistence.

I avoided [1] classes, clubs and activities which were evidently abused for their signaling effects more than they were actually enjoyed. I was one of very few among the top 1% of my class who didn't force themselves into AP US History, AP Chemistry, etc. These classes were not of immediate value or interest to me, so I simply didn't take them. [2] I spent my time on more productive tasks that were of immediate utility and / or greatly increased my human capital: contracting as a web developer, studying foreign languages, linguistics, math, philosophy, … outside of school, and networking with developers online and in my city.

I can confirm after meeting fellow Stanford students and getting clear answers from admission officers that students can rarely, if ever, force themselves into a top-tier school with a strategy dominated by signaling. These schools [3] put an extreme amount of weight on essays. [4] Test scores and class load, areas which often earn the most focus from students, parents, and teachers, are all secondary to the image a student projects through his or her written responses.

Signaling should be far less central to a high school strategy than is currently the norm. Top-performing students need to realize that the surest way into a selective university is:

1. Search out a field, idea or problem that fascinates you. Forget about how "significant" or "impressive" this issue might look on paper to an admissions officer. In fact, forget about admissions altogether.
2. Pursue your own goals in this field relentlessly. If you like to knit, open an Etsy shop and start marketing or offering classes locally. If you like to cook, make your own YouTube cooking show or start a blog to publish your own recipes.
3. Write clearly and honestly about your achievements in your application essays. Remember to show, not tell: use your accomplishments as proof of your work ethic, ambition, etc., rather than expecting a reader to trust you. (Your English teachers will likely have advice on how to include lots of information about your achievements while avoiding outright bragging.)

tl;dr: "Follow your passion" is really true. Students should rarely engage in activities solely for the sake of signaling. Evidence of a true passion can show through in application essays, and will mean more than 10 club presidencies or 50 letters of recommendation. Rip out of the chains of high school and do something that you're passionate about!

I'd highly recommend How to Be a High School Superstar for any current high schoolers. This book really changed my view on academics, and I'm not sure I would be at Stanford without it. (No affiliation, just a happy customer!)

Footnotes

1. Explicitly so, as an intentional strategy.
2. This earned me lots of confused looks over the years. People would ask, "Why aren't you in APUSH?" as if the accelerated class were the default choice.
3. I speak for Stanford mostly, but I know (anecdotally) that schools of similar caliber have the same kind of philosophy regarding selection of students.
4. Stanford's application had 10 writing prompts, 8 of which were short-answer (just a few sentences), carefully designed and refined over the years to suss out the real qualities of a student.