For the last two jobs I got by actually actively seeking out an opening rather than being contacted by a recruiter, I only send out 2-3 applications each, but with a cover email that was custom to each company.
On one occasion I had a 100% interview rate, on the second one a 66% one (1 out of the three companies had an automated screening system and I'm pretty sure I was too expensive for them).
Whatever experience you have, it won't get you through the door if you give less than a single sentence as a cover letter.
Whatever cover letter you have, it won't get you through the door if you have no experience in your resume.
Have some experiences + have a few sentences cover letter. That's the magic recipe. If you have any less than that, you're going with a disadvantage.