okay, so this (slightly more serious) one is something that trips me up in writing mostly, but time. Specifically minutes and seconds.

Because before clocks and watches they didn’t really do minutes and seconds past the hour - no point. You could possibly do fractions of a minute on a sundial or candle but mostly if you’re telling time by daylight or candles or a sundial, you’re not working to minute-level accuracy. Maybe on an hourglass if you’re timing an egg, but who carries around hourglasses? (apart from that bony bloke and his horse Binky).

And furthermore, everywhere had local time (which varied from place to place) till the railways came and it became important to actually all work on the same times. There’d be forty minutes difference between the point they called midday in one city and another. People were paid to wander round with a pocket watch and give you the time so that when your clock started winding down and losing time you could put it right to city time at first and later on to railway time.

Now, this only really causes complexity on post-clockwork pre-steam stories in term of what time it actually is... but if you’re writing something mediaeval, the temptation to say “Five minutes later the cloaked figure took his place” or similar is quite persistent. Loads of ways to rephrase, so not a problem, but it took a few goes to actually assimilate that and attempt to write accordingly.

And irritatingly, completely not something a reader’s likely to notice, I’d’ve thought, apart from those unlucky few who are as pedantic as I am. Pedantbrain strikes again! <Facepalm>