Interestingly, when I plug in a camera SD card, and (oops) quick look a photo on the card, I have to force eject the card, or just live with the annoying message on the top right of the display. It's in effect a read-only memory, though I suspect that quick look (preview in disguise?) touches something. And as for flipping the read-only switch, I ain't doing that. I will surely lose a timely photo that way.
FWIW, I read that deep-cycling a battery at the outset will help it live longer (forgot the article) so I am resisting the urge to float-charge a Christmas Special ipad that I got mainly to stream classical music over the internet. I'll give it some deep cycles.