In all my travels, to the west coast, to the UK, to Florida, I have had one bag misdirected...just one. And that flight connected at Ohare...so I have to wonder if that's where the misdirection happened. But, I had my bag before noon the following day....Delta delivered it to our door, even though we were 45 mins out from SeaTac.
Misdirected/lost luggage is just nothing I'm concerned about. For one thing, I never pack anything I can't afford to lose. That stuff all goes in my carryon. I also tend to divvy up everyone's stuff, so that no one bag holds just one person's stuff. If a bag does go missing, at least everyone will have some stuff with them.
As noted, always, always, pack a carryon with anyting you might need for 24 hrs. I didn't follow that rule one time..I was headed home, on NYE, a few years ago. Our flight got diverted. We had two choices....get off in Philly, but without our bags and get a flight to TFGreen the next morning, or stay with the flight and return to FtLauderdale and get our checked bags there, and get a flight the next morning. Because I stupidly figured I was heading home, I didn't pack anything I needed for the night in my carryon. So....we had to fly back to Florida, and then make the flight all over again the next morning. It was not fun. If I had had that carryon packed correctly, we could have stayed in Philly, gotten a good night's sleep, and taken a much shorter flight the next day. Be prepared!!!