Ben Torah,
Dr. Pepper is correct that I’m an engineer, though I’m not working outside the home now.
I barely used Fourier Transforms after I learned them. I think I used them a few times for grad courses but never on the job. However, I needed to understand them to do well in Diff Eq, which was a prerequisite for various undergrad and grad courses.
Having a good GPA helped me qualify for a scholarship from the National Science Foundation that supported me through grad school. And all that helped me when I was applying for jobs too.
And of course, the ability to acquire new skills through independent study is essential no matter what you do.