Thanks! With this handy way to remember things, I no longer need a mnemonic 
(Despite me ribbing you, I am actually grateful - I had never thought about the sequence of long/short months.)
Minus the Caesars part, that’s exactly how my brain remembers it. I basically just remember July and August are 31, and the rest falls into a pattern from there. (Though, to be honest, by now I don’t even need to think that — it’s just engrained how many days each month has.)
But… wouldn’t that be the wrong direction?
No, I’ve seen her do this many times. If you tell her to go left, she holds right and left hands up with the backs of her hands facing her. She traces the “L” made by her left finger/thumb with her right index finger and says “left”. It’s weird, but it’s how she navigates life.
Imagine being dyslexic on top of having left-right confusion, and not being sure which letter “L” is oriented correctly and which is backwards.
Yeah, it did seem very unlikely, but it was what initially helped me to remember the months, so it was still helpful.
For those who simply remember that the months alternate long/short but with the two consecutive long months of July and August, note that the finger-counting (or knuckle-counting) trick is based on the same observation.
This bothers me as well.
The funny thing is, I always seem to forget how the knuckle-counting trick works (most likely because I don’t use it enough – I just know there’s a way of counting days in months using your knuckles. Yes, it’s simple and, looking at my knuckles, I can figure out how to make it work [actually, there’s a few methods you can use]. I believe the way I was originally taught was to go from left knuckle to right knuckle and reverse direction, double counting the right-most knuckle, but I would forget that double counting part. Wrapping around to the first knuckle or continuing on the next hand seems to be more fool-proof.)
The most accurate, up to the minute way to determine number of days in the month is even easier for most people. Say “Hey Siri” or “Hey google” and then ask. 
So back to the OP from the sidetrack, I’ve very rarely found myself in trouble by giving a more detailed/complete answer than a minimalist answer. In fact, I’d say almost anytime I’ve given a concise answer (again not just directions) it is for someone to come back to ask for confirmation. So I’m in the pro-redundant directions clique.
In Australia, which drivers on the left, at N way stop signs, the driver on the right has right of way… so whether its “drive on the left” or “drive on the right”, its the dextrous side with right of way. So in a way, your someone who thinks it is universal is correct, if the universe means the humans on earth.
Sinister used to mean left hand side… the sinister hand… so you could be ambi-sinisteral … two left hands…
As to using the extra word… You know how if you have a digital TV, and use another amplifier, the sound could be out of sync with the pictures ? So you introduce a lag to the TV to correct for the lag to the amplifer…
Well, there’s parts of the brain, and they have their lag times… saying the word hand may have the effect of wasting time, a lag time, so as to let the parts of the brain become settled on whether it was correct when it said the direction … or a hang over from when checking their literal hand is matching at that point of time, like a reminder and a period of time for that to be done…
But anyway, its idiom… which is called that because its a result of use … not the sum of the parts.
Your Left hand, by sum of parts, has about half your fingers, typically. By idiom, it means a direction. You could say “that area on the left”, “in the direction of left”. or some other awkward construct…
Or just “the left”/“a left”.
The only way I learned right from left at all is that when I was a kid I had a wart on my right hand. If the woman you speak of (and by the way, the pulchritude comment was offensive), has any degree of dyscalculia, which affects the part of the brain that does abstract mapping among other things like numeric facility, she probably has other workarounds as well, that you don’t know about.
It has nothing to do with either intelligence or personal appearance.
Offensive to whom? The friend I was describing would take no offense, as we joke about it all the time.
I’ll let moderators handle it, if you can’t figure it out.
This is not something juvenile, it’s just habit and there’s nothing wrong with it as it’s understandable to all.
There are tons of examples. VIN number, etc.