Are you wondering about the process now with the REA/ED apps in? This was eye-opening.
https://www.reddit.com/r/ApplyingToCollege/comments/1ookdf9/read_my_application_from_top_to_bottom_took_over/
It's not determining whether we want a candidate in 3-5 minutes. That actually happens in committee discussions, if the school has one. I usually spent on average 5 minutes for reading applications. The time reading is just to get a sense of who is in the pool and whether or not we should bring them into committee. I guess to some that means deciding who we want, but I guess I define it differently.
I'll walk through just a bit how I read applications.
Reading:
On my slate view, I can see general data. Think test scores, majors applied to, region, etc. Metadata, I guess? This takes maybe 15-30 seconds to comb over, sometimes less.
I go straight to your transcript. If this is the first student I'm reading in a school group, might take some more time to really understand what's going on (some transcripts are HORRIBLE to read and understand. Others are quite straight forward). I'm essentially only looking for your grades in core classes. If it's a really easy, readable transcript, this takes a couple of seconds. If it's a wonky transcript (i.e., the classes aren't straightforward to read), maybe a minute.
Then I go to LORs. I'm reading fast, usually looking for superlative praise and examples to substantiate that. Most LORs are mid, so it's not hard to quickly sift through. If there is superlative praise, I'll note it down. Usually a minute or two.
Then I get to your common app. I see what your parents do/their degrees if any and future plans. This is super fast. Awards too can be fast. Then I get to your activities. I'm taking note of what I think is particularly compelling and impactful with leadership. This takes 30 seconds or so. By the time I get to your essay and supps, that usually takes another 2 minutes of reading for me. I've always been a fast reader with a good sense of comprehension.
So all of that was about 5 minutes or so. It can be longer if a case is really strong or complicated, but most students won't have complex cases. It'll take me maybe another minute to write my notes down, which is just summary of all parts of the app (ECs, grades, essays, LORs). By this point, I will have a general sense of whether or not the student is competitive. If not, I can deny. If they are competitive, I'll send them to a second read.
My second reader will do the same things I've done and offer their thoughts. I'll look over that, and decide if I actually want to bring them into committee. Imagine I do this across 30ish students. Once I get all 30 cases back from my second read, I spend some time mulling over who I actually want to bring in committee, and who probably won't make the cut after a second read from another person. Once I'm in committee, I pitch the student and we discuss. That takes another 5 to 10 minutes, sometimes longer depending on the complexity of the file. And other AOs will have access to the file as I pitch it, so it's all kind of a parallelized process of understanding an application and talking about it.