Every week this term, on both Tuesdays and Thursdays, I teach a class in the Francis Bancroft building on our university campus. Twice so far this year (so that's 20% of the times I've been into the building), there has been a security guard on the door checking the ID of every person going in.
Now, whatever the merits of having someone check the ID of everyone entering a university building, whatever the point of this exercise is supposed to be, surely it is rendered *entirely* useless if you don't do it every day. If the purpose is to stop people stealing things (there are plenty of old computers which must be worth tens of pounds on the black market) then surely they'll just come in and steal them on the days when you don't do the checks. If the point is... well, I actually have no idea what else the point could be, it's a university campus, not a Government Intelligence building.
There can be literally no point whatsoever in having these security checks unless they're done regularly (in much the same way as there can be no point whatsoever having full-body scanners in airports unless you also perform cavity searches). Security which is this easy to circumvent is not security, it's theatre.