No ones outages. Yet how many people think about the errors made. You know those times when you leave a burner on, ATM card in the machine, original in the copier. OK who goes to the copier any more like they used to. But, that doesn't mean you are making errors all the time. Running data center infrastructure is so full of potential procedural errors the disciplined have figured out they need to invest in detecting and reducing errors.
Here is a paper written in 1995 on Working Memory, the short term memory you use to do process the new and old information. http://chil.rice.edu/byrne/Pubs/git-cogsci-95-06.pdf