This comment made me take a brief inventory of some of the systems I have internalized to the point where I don't think about them as being memorized: the rules of the road while driving, the conventions of UNIX-style commands, unit conversions, hotkeys in (and across) applications, how street addresses and road navigation works, how to use a search engine, how to compose a sentence in English, and so on.
At some point in my life, all of these seemed needlessly complex and arbitrary to me, but they don't anymore (at least unless I think too hard about them). I don't think about them unless I have to teach them to someone else, at which point I start thinking about how seriously broken they are.
I suppose that if I needed to get the day of the week from any date in history, and used this algorithm often enough, I'd eventually think of it as something I didn't have to memorize either.
At some point in my life, all of these seemed needlessly complex and arbitrary to me, but they don't anymore (at least unless I think too hard about them). I don't think about them unless I have to teach them to someone else, at which point I start thinking about how seriously broken they are.
I suppose that if I needed to get the day of the week from any date in history, and used this algorithm often enough, I'd eventually think of it as something I didn't have to memorize either.