As an applicant, I often discover reasons for or against applying for a company during the application process.
As an interviewer, it's not a dealbreaker, but it definitely stands out when someone puts in the effort to write a clear, thoughtful application.
So it would depend heavily on what the "savings" are here. Where does "20+ hours" come from?
The “20+ hours” is mostly coming from the mechanical stuff: re-entering the same work history, dates, education, addresses, citizenship questions, etc. over and over across different ATSs. Not the cover letter, not the custom questions.
Ideally, the goal would be to reduce fatigue so people can put more effort into the thoughtful parts, not less.