Depends. Some have a paranoid mode without caching, because then a physical attacker cannot snip a cable and then use a stolen keycard as easily or something. We had an audit force us to disable caching, which promptly went south at a power outage 2 months later where the electricians couldn't get into the switch room anymore. The door was easy to overcome, however, just a little fiddling with a credit card, no heroic hydraulic press story ;)