This has been driving me a little bit crazy since upgrading to iOS 6!
Whenever I get a notification when the phone is locked, I tap on the alert, but nearly always the screen turns off again before VoiceOver has finished reading the notification.
I'm not aware of a setting that adjusts the time before the screen relocks. Is there one?
I know that I could turn on the setting that has VoiceOver automatically read all lockscreen notifications, but I don't want this.