Not as much as he thinks. Not that he didn't put in the effort, but I was wandering around right in front of his post with an abomination, a blood mage, and the pirate scourge of the seven seas and he never seemed to find anything wrong with it.
Not that I'm implying that Cullen is hilariously incompetent or anything, I'm just saying working for the Inquisitor really improved his eyesight.