All guns *can* fail. If your life depends on it, you'd better know how to clear a jam. And if you are wise, you have a backup weapon.
That said, I find that my Glock needs grease on the slide. Oil doesn't cut it. I use Tetra gun grease. Apply it, buff it out and repeat. My slide moves like silk and never a stovepipe any more.
It is very much worth watching a 6 minute Clint Smith "tap and rack" video:
http://www.youtube.com/watch?v=BfyULpEhmug
/*tom*/