[Sphinx]

My personal rule of thumb for astral security is what I call the "guards and wards" rule: anyplace with guards will probably have wards. Any company that can afford the salaries of multiple full-time security goons can also afford to have a magician come around once a month to renew their magical wards. The more security goons there are, the better and more extensive the wards are likely to be. Characters with personal quickenings should be especially wary.

On-duty security mages are another story. There simply aren't enough of those to go around. Only the best-funded sites will have a security magician or spirit on premises ... or locations where a magician has a personal interest.

[Stainless Steel Devil Rat]

On-duty mages/spirits would surely be rare in the grand scheme of things, but Shadowrunners aren't hired to break in to places like Taco Temple or Stuffer Shack. 

At any rate: if you have the budget to pay for security, then you have the budget for a "mage on call" subscription to send a spirit or astral mage to come investigate a reported disturbance.  You can get from anywhere in the sprawl to anywhere else in the sprawl PDQ in astral.

[Xenon]

The section on Security in the Sixth World in the 5th ed book specifically states that magic barriers are an extremely cost-effective astral security measure. While no prices are given, in SR4, it specifically mentions that firms often do wards, and a ward takes (Force) hours to complete. One magician can ward an area of Magic x50 cubic meters in one go, and multiple magicians can pool their power to ward larger areas. Those firms typically charge 100 nuyen per hour (per magician) for the wards, which last for a number of weeks equal to the number of hits on the Magic+Willpower test. In other words, wards are dirt cheap, and anyone who has a few hundred nuyen every few weeks can afford at least a force 3-5 ward on an office or something, especially if they're a mundane. So you should expect wards to be fairly common in areas where the individual has the means to get them. Wards aren't like high tech security systems. They're the astral equivalent of the maglock.

[SunRunner]

Xenon did you even read my post? I stated pretty clearly that alot of places are going to have wards, they are in fact pretty common. its active magical security that is pretty rare. I even defined that in my post as people with the ability to astrally perceive. As was pointed out earlier wards are nice, but force 4 or 5 wards are not even gonna slow down the kinds of mages that carry around multiple quickened spells in my experience. And if you dont have some one looking on the astral plane and going excuse me please terminate all active spells before entering out establishment NO one knows you walked through a ward with several active spells.