The Reaper f***s up all of the time. He's a little bit of a cowboy and shoots first, asks questions later. Also, most of the time he's high. You can't really blame him. It's a thankless job. Nobody is ever happy to see you. People curse you all of the time. The only reason he doesn't slit his wrists is the drugs.
So figure if you're depressed and stoned, you're going to make mistakes. A lot of mistakes. Every once in a while he'll catch himself before it's too late and that's when you have people coming back from the dead with near death experiences. God hates giving people a glimpse of the other side, but what's he going to do? Hire someone else. Yeah, good luck with that.