A well-designed security operation eliminates any easy approach for an incursion and finds a way to neutralize or minimize any advantage an intruder might be able to find. This cannot be accomplished without everything that may be an influence being accounted for; from nearby traffic patterns to how the building directs the flow of pedestrians. Of course, most important is the operating procedure of security personnel, and how they utilize the tools at their disposal.
A camera is one of the most valuable and proven tools in the security field. But its effectiveness by itself is severely limited. Even if an intruder passes through its sight, the video feed must be actively monitored in order to know that action needs to be taken. But staying focused while looking at video monitors for an extended length of time is not humanly possible; the vast majority of people have the ability to remain consistently attentive enough to notice an out of place threat for only 30 minutes of monitoring a repetitive image before losing focus. In addition, even if images of the intruder are recorded, they will be of little to no value if the intruder has taken steps to hide his identity, and the damage will have been done.
This is one example of how considerations must be made to merge all security measures into a unified plan, with all elements being coordinated to take maximum advantage of their security benefits while working together to overcome their weaknesses. Though it has shortcomings on its own, there are many options like multiple monitoring officers, or regular rounds in the threatened areas between periods of studying video feeds that make up for them.