As a programming language developer, this is a persistent difficulty I’ve slowly been training myself out of. I know how to use a language I’ve written because,

As a programming language developer, this is a persistent difficulty I’ve slowly been training myself out of. I know how to use a language I’ve written because, well, I wrote it—but if I sit down with a new user for an hour, they discover all the bugs I knew about and a few I didn’t! (This applies to all kinds of software, of course, it’s just particularly noticeable with developer tools.) But an hour of someone’s time is hard to get, and once they’ve used the software a bit, they’re spent—you can’t make them naïve again. So fuzzing and randomised property testing have begun to take their place for me, as well as an adversarial dialogue in my own mind of “What happens if I try this stupid thing?” versus “The software should patiently and correctly do something reasonable, with no casualties, no matter what stupid thing the user does”, each constantly trying to one-up the other. It’s pretty fun, actually—I’ve thought of getting a “devil duck” and an “angel duck” to personify them, in addition to the standard-issue debugging duck. :)