One thing every writer must learn is that rejection lurks around every corner. Even if you think you've crafted the Greatest Story Ever, odds are the person reading it will not agree. They will likely look at your story, compare it to the 3,000 others they've read that week, and then send out a nice, simple form rejection.
The same goes for query letters. Sure, your book idea is a can't-miss-blockbuster-bestseller! But thousands of other writers believe the same thing about their work and have also sent their query letter to the same agent. The form rejection becomes much easier to use when agents are buried beneath a deluge of submissions. Then again, some may not even bother to reply at all, a despicable practice that leaves writers stranded in purgatory: "Did my email get sent to their spam folder?"; "Should I query since I haven't heard back in two months?"; or "Did they simply not like it?"
Over the past eight months, I've sent out 21 separate submissions for short stories. The markets have varied from small to pro. Of these 21 submissions, six stories have been accepted. That's a batting average of .285, certainly not Cooperstown numbers, but good enough to hang around as a utility player for a while. I would love love love for my acceptance rate to be higher, but that's tough. Even the smallest publications get hundreds of submissions that vary greatly in quality...and these markets typically offer token or no compensation! When it gets to the bigger publications, competition gets even tougher.
So yeah, I've had 15 rejections and six acceptances. That's a landslide in favor of rejections.
However, let's put it this way. If I wrote a hundred different stories and failed to send out a single submission, what's my batting average then? That's a big oh-fer; a failure percentage of 100%. I'd take 28.5% success over 100% failure any day.
That's because every story you don't send is an automatic rejection.