Not sure what OS you're running, but I'm on Windows and use a program called "FastCopy". It's a lifesaver for coping my scrapping supplies to my external drives. You can download it here:
https://download.cnet.com/FastCopy/3...-10905019.html
I have mine set to only copy files if their modified timestamp is newer than what's already on the external drive, so it's not trying to copy my entire stash each time I run it. I read the help file to get everything set up the way I wanted it, but if you end up using this and have questions I could help.