A matter of timing.
So much of applying for a job is timing. Assuming you’re sending out concise, intelligent, relevant cover letters, assuming that your resume is relevant to your skills and to the people you’re sending it off to, then a great part of getting your ideal job is making sure that the people who make the decisions actually see your resume and cover letter!
Don’t presume, for example, that just because most people have smartphones, if you send your resume at 11pm or on Saturday evening, that it’ll automatically be seen by a human. That resume might sit in the depths of someone’s email, buried under the next mornings junk mail…and 500 other applications. And forgotten. Ignored. You end up not getting rejected as much as missing your chance: were you rejected, or did no one see your email because it came in Sunday evening and was buried under 1000 others on Monday morning?
Applying for a new job is especially hard when you’re working, full time, at another job, since you have to be discreet. But instead of sending off resumes late at night, or on the weekend, when they may not be looked at for a significant period, and thus missing an opportunity…consider writing the letter and cover letter after work or on the weekend, preparing the documents in your email, and on the next business day, at the end of lunch, or during a coffee break, take a walk to the nearest Starbucks or McDonalds, or Barnes & Noble—anyplace with WiFi—and hitting send. That way, the recipient will (ideally) see your email right as they’re sitting at your desk. That way, you’re making it easy for you to achieve your goals.