Our last hiring round we got probably 200 applicants. At least 95% seemed to just be automated submissions, no cover letter just a resume, despite our application asking specifically for a cover saying why you were a great fit. We had 3 of our most senior people reviewing these applications (our of a company of 8).

Most of the time we were digging through dense resumes trying to pick out the 1 or 2 things that matched our technology stack. We figure the cover is the place you tell us why we should talk to you if you only have 1-2 technology overlap, so most resumes we spent 30-60 seconds on and then ditched.

We interviewed 3 people out of that, and they were both really super junior. We were considering hiring one of them as a "maybe she could learn the position". Then I sent out one more round of "if you know anyone" to my personal network (which I had previously done a few months earlier), and got one personal reference to a guy we ended up hiring.