No its not rocket science but **** happens.
And its not a small piece of **** its a whopping great big $50 000 could poetentially kill someone on the outside turd.
I have fogotten to arm a door. The pin wouldn't come out and by the time I wrenched it out I just closed the cover and walked away. But because we cross check we realised straight away.
I think it takes 2 seconds and doesn't cost the company any money to do so so why not cross check