Should I copy-and-paste my cover letter?
Short answer: No.
Long answer: Do not copy-and-paste the same cover letter into every job application you submit. Rather, think about your cover letter as your first opportunity (perhaps even your only opportunity) to convince the hiring manager to look at your resume.
When you think about it this way it becomes clear that your cover letter should not just restate what is already in your resume. Rather, it should highlight the things about you and your skills that make you the exact best applicant for the job at hand. It’s that easy to maximize your chances of moving ahead in the applicant pool.
P.S. We cannot tell you how many times we have read cover letters that contained references to responsibilities that were not part of the job opportunity at hand. This screams cut-and-paste. We have also read countless cover letters that name a different employer somewhere in the body of the document. This not only screams cut-and-paste it also suggests the applicant is not truly interested in the job they are applying for (as they did not invest enough time in the application process to write a fresh cover letter).