Reminds me of a book I read by a physicist called Feynman who used to work in top secret stuff for the US military in which he described how when he had a difficult problem to solve, he'd think about it hard, then 'leave it to simmer' for a while - and in the meantime, to keep the rest of his brain ticking over, and just for fun, he took to safecracking. In the course of which he discovered among other things that of the very large and very complex and very expensive safes in the building - the ones containing the very very very secret paperwork - about a quarter still had the default combination with which they were shipped from the factory. Almost all the others were set to some really uncrackable code such as the owner's date of birth or home phone number. Barely 20% had anything resembling real security - ie, remained uncracked after he'd been at it for ten minutes or so.