that's the reactive approach to pseudo-security, searching for the same means the last lunatic used. Someone tried to use liquids...so search for liquids. Someone hid something in his shoes, so now we need to screen shoes. Unfortunately, the next lunatic will be more ingenious, and come up with something new.
I do have some sympathy with this position. Whether an incident happens, the authorities always react to it, essentially locking the stable door after the horse has bolted.
Take not allowing traffic to stop in front of (UK) airport terminals - because a pair of not overly bright terrorists tried to drive a 4x4 into Glasgow airport's terminal. Sure, the great big concrete blocks will deter a repeat, but supposing the next candidates decide to blow their 4x4 up in the confines of a multistorey car park - do we then ban cars from them? The carnage could be equally as great.
Terrorists, at least the brains of the outfits, aren't stupid, they are often well educated and are unlikely to use the same modus operandii twice. Putting ever tighter restrictions in place following each event, ensures that the terrorist wins, without losing a single operative.
Surely the way ahead is to have a more targeted covert approach to security rather than the blanket approach as happens today.