Android OS is a system of file structure and folders: and it wants its folders where it wants it. Just let it do its thing.
I advise against formatting any flash memory like SD cards or jump drives, and here's why...
All flash memory (anything using chips for storage) has a lifespan measured in read/write cycles. Modern flash memory chips, made by reputable manufacturers, have lifespans that should last years and years. Of course, the more data is written to them and modified, the faster those read/write cycles get used. Formatting such a chip is a monumental expense of read/write cycles: especially a full format, where every bit is rewritten and zeroed out.
Delete data, sure: but I recommend a format only if all other means of correcting a memory module corruption have failed.
From what I have read about SD cards, as far as professional photographers and the like, modern day cards have a balancing system built in that evens out the wear over the entire card, ie.you won't be writing over the same location repeatedly.
Also, formatting the card, although using up a write cycle, is how the balancing system locates and then eliminates bad sectors from being used again.
This is why professionals that rely on these things format the cards regularly.
Also, by the same folks, if a card is to fail it will be early on or after quite a while.
Early on means within the first 3 weeks or so.
My 256 GB card failed within this early timeframe.
So the professionals will use a card multiple times and reformat it multiple times as well before they try to use it for anything that really matters.
To be honest, I have always tried to baby my cards, and it has not paid off for me that well.
Perhaps I should donate another $50 or so to the experiment (the price of another 256 GB card) and treat a card 'like crap' to see what happens.
Seriously, it may well be worth the cash just to learn.
I will say, however, that I have noticed an improvement in my devices (two tested) when there is no or an empty SD card in them.
This means that a card does slow a device down to a certain degree, and as the card fills up this slowness increases.
(My 7.1.1 can attest to this.)
When the 256GB card crashed, the device basically locked up except for the launcher, where just before that it was working just fine.
I was not doing anything with the card at the time, but when it went, the device was non-functional (no apps would launch) until the card was ejected from it.
I restarted the phone, and then came the 'SD card corrupted' notification.
This means that when a card is in the device, the system is always doing something with it.
I think that is exactly what happened to
@Trom 's card, and the rest of the above is my reasoning that it should be formatted by the device that is destined to use it.
The device saw directories that it did not make, and proceeded to 'fix' that.
Reformatting in the device that will use it will definitely solve that issue.
Just as when someone deletes all the folders that an Android automatically puts onto a card, they will reappear soon after- and not always immediately.
If it is a new card, then one more write cycle should be as nothing to it, as the card makers advertise that hundreds of thousands of write cycles are quite possible.
