Run&Gun
Veteran
Like a lot of people, I use Finder to copy. I somehow had an issue a a few years ago(don't remember the camera/card) and I did a drag 'n drop from the card to the back-up folder. When it was done, the card was empty. What?! The data was in the back-up location, but the card showed nothing on it. After that, I've always tried to make a conscious effort to Copy 'n Paste instead of just Drag 'n Drop.