I've worked with multiple recruiters for the past 8 years and have seen the good and the bad. (ivyexec.com)
I've heard multiple recruiters discuss this question and while there are many times when a cover letter may not be required, I believe they should never be ignored during any job search. (careerdirectors.com)
A large company may employ multiple recruiters, and that can increase the odds that the same individual will not spot multiple applications from the same person. (thejobnetwork.com)