If you are looking for some job, any job, this attitude may make some sense. Say, because you are unemployed or because you are truly miserable in your current position. Even with a pretty crummy employment market at the moment, this is not most people.
If you are looking for a next position, say because you have a big life change coming, want career advancement, or just plain feel like it's time for a change, this doesn't make sense at all. Spewing uncountable copies of your resume to the four winds and hoping might land you a job. If so, my guess is at some company you have no connection to, no passion for, and likely no reason but the pay check to keep going. This is not a recipe for happiness OR success in the new job.
I frankly can't imagine being willing to leave my current position for another one unless it was more than sufficiently exciting to justify customizing a resume and cover letter. Heck, the last time I did that it was for an internal transfer. Probably the next time, too. Red Hat is an excellent fit for me. Of course, I also find the whole idea of finding jobs through any form of job add rather improbable. I've literally never been hired for a job that I had seen an add for before I had talked with the hiring manager. Do people really get jobs that way in statistically significant numbers?