[otrs] Unlock Timing out

What is the reason for the Unlock Time out in OTRS? I have created a Queue called Projects and there are 3 subqueues under this. In one of the subqueue's of Projects a person will take posesion of the ticket but then about an hour later if you look in the history root@localhost has unlocked it back to the main Queue. the Unlock timeout is set to 5, I am assuming that if it is not worked on in 5 hours that the system takes over and unlocks the ticket.... is there any reason Not to set it to 0 to default it to no unlock, so that root will not unlock the ticket? if anyone has seen this please let me know thanks