Slip and turn: great post. I'm work in a responsible job in another sector where I have to do the equivalent of "getting my knees dirty" every single damn day. I work on the basis of assuming that other people haven't done what they are supposed to have done, and about 1% of the time I'm right. Sure, in situations like this problems often have organisational causes as much as individual ones but checks and double checks are built into systems for a reason. Complacency can quite literally be a killer.