Well, almost any implementation would be better than the current one. He is right, what they should do instead.. is a progressive sweep of the entire area.. as intelligent people may do. You are a security guard, with a gun, and no phone to the police. You know somebody is on the premises, how do you go about ensuring they are gone? You perform a sweep, you check everywhere. If it is dark somewhere you use light. So bandits might use torches where zombies might just sweep the area and all the corners two or three times. Have them go anywhere that is open to travel. If the problem is behavioural, fix the behaviour not the time they perform it for.