Application Switcher doesn't always switch apps after releasing cmd-tab. I'm pretty sure that it only ever doesn't switch when I'm just switching to the next app. I don't think I've ever noticed it not switch when switching to an app that's more than one over from the next, if that makes sense. In the case of switching to the next app, it will occasionally just continue to show the application switcher and I eventually have to escape out of it. Here's a video demonstrating what I'm talking about (you can see the keys I'm pressing in the bottom middle of the video):
Am I doing something wrong?