So, I'm quite surprised that when the Romans moved the start of the year from March to January they didn't take the opportunity to rename September through to December in a way that reflected their revised position. By that time, presumably, these had become mere arbitrary counters to them, rather than words with intrinsic meaning. Similarly, the missionaries who converted the English surely missed a trick when they left the days of the week for the pagan gods to swank around in. This doesn't strike me as a case like that of, say, building churches within henges, or converting the goddess Brighid to St. Bridget, since no Christian substitution was made: the names were, again, just counters.
As with etymology, so with mnemonics - which sometimes indeed overlap. I told one of my Japanese friends the other day that I remember the Japanese word for "fresh" (shinsen = 新鮮) by looking at the characters, which consist of a kanji meaning "new" (新) followed by a kanji which is itself made up of the kanji for fish and sheep (鮮). So, I think of new fish or new sheep being "fresh". What relation this bears to the actual etymology of the word I've no idea, but it seems a pretty obvious mnemonic. She however had never noticed this, and found it very amusing when I pointed it out. No doubt the same experience could be had in reverse - indeed, I'll look out for it.