I read all of them, even the greyed out ones, until I'd read enough to trust that the HR team's filter was well-calibrated, and I also let the HR team know when they got it right/wrong so they could improve their filtering process.
Overall it worked great but I understand that such functional HR teams are the exception, not the rule.
Edit: My apologies everyone. I actually read this as "cover letter" instead of CV.
I agree a resume (as noted below) should be required, but CV (academic style) is probably a US term not applicable here.
Sorry!
edit: saw another response which said a cv was a resume, this is correct. In the UK we use Curriculum Vitae (CV) instead of resume. They are the same thing. Not sure what you may have thought a CV was, however I would be interested to know.