Depth or Breadth in ECs? The types of students who make it in......

<p>Okay. So I (probably along with many others) don’t quite understand college admissions.
They tell you to focus and fully develop on just a handful of your interests and classes, but I know so many people who haven’t done that.
And according to a lot of the stats found here, there are many students who do a wide variety of ECs and don’t develop any of them extremely well. Yet, they still get into prestigious schools.
The question is how do admission offices distinguish the depth from breadth? If a student lists 5 different ECs (none of them are very developed-mediocre achievements) and another lists 1 EC (VERY solid- like being a prez of 200+ member club), how will they know who to choose?
Or what if a student wants to focus on a new effort (like developing a 5-person member club) and spends time developing it (and thus, doesn’t focus on other activities). How will they know this information?
How do admissions officers recognize passion?
And how do you keep a life doing all this?</p>