Then I stopped bothering when it's super obvious that isn't working. Particularly, on Linkedin you could see the number of people that has applied (maybe a paid feature, i don't remember now). And for any entry level software engineering and data science position it's always in the 100s.

The one recruiter that I had contact with did more work than all of these. I've since switched jobs (to one of the FAANG) and that was through recruiter too.

I also don't think field matters until one gets to PhD levels, which I did not.