A resume is an important tool, but it can't get you a job. Only people can do that. If you want your job search to be successful, concentrate on people and prepare your resume to suit their needs.
Networking with follow-up is the most effective. The key to a successful job search is contacts. Most people can sell themselves better in person than on paper. While the tailored resumes you send to search firms, ads and direct mail targets are important and deserve your attention, they will never possess the power of a good relationship.
Replying to all resumes would be the polite thing to do, but often it simply isn't practical. If a company receives 200 responses for an ad, or experiences a continual deluge of unsolicited resumes, it would spend an inordinate amount of time sending acknowledgments. If you really want a receipt for your resume, send a stamped, self-addressed postcard asking for one. If you make it easy, the human resources department will comply.