It hasnt been specifically mentioned, so in order to be told im wrong, or prehaps shed some light for someone. The database locking usage is similar to Gos auto reboot, as in its nice to know that if your phone is removed from your person that it will return to a more secure state automatically, for me setting the timer to 2hrs works well, i use the phone during the day for work so the first time a 2hr block of time with me not unlocking the phone occurs is when im home having tea or sleeping when im not interested in being notified of calls/messages.... and of course if i am parted with my phone then 2hrs is not a huge window.