I used to have a 1.5 page resume covering boilerplate, keywords, and highlights with a longer cover letter giving more detailed background. In a post interview critique I was told that the resume was too sparse. I pointed out the cover letter has what he wanted to see but of course that never made it to his inbox. New tech job search can't reliably manage two digital documents so I just merged them into one as a safety precaution.
The notion of a cover letter is pretty outdated for most jobs. The people still teaching their use are firmly rooted in the age of sending unsolicited job applications via mail that will be screened by a human.
I still do them for some desirable ones - eg if covid hadn't intervened id have done a custom cover letter and cv for the grade 6-7 Civil service job I got pitched (Colonel to brigadier Range)
(that's around the same level of Matt Cutts Current Job)
The notion of a cover letter is pretty outdated for most jobs. The people still teaching their use are firmly rooted in the age of sending unsolicited job applications via mail that will be screened by a human.