I am VERY behind, and don't scrap any in one order or even semblance of order! So, I don't really have photos that don't get used (because who knows, I could still use them).
That being said, travel items get printed the most around here. If a photo didn't make it into a layout, to make it into the album...I just leave it be! I like to label all groupings of photos, and when a folder has been scrapped, I edit the title to say "DONE" so that I know not to rescrap those photos. But not every photo gets scrapped, so they just stay in their folder with the rest of them. I don't delete any GOOD photos, regardless of if I scrapped them or not. Only photos I delete are bad ones to start. I have tried to teach my girls good photography skills, so that we are limited on the bad ones.
Oh, I guess I should say all our photos, except the most recent few months, are removed from the laptop and phones onto 2 different EHDs. One is the main that I use when I scrap, the 2nd is just a backup. In 2020, when everything else was crazy...I had my laptop and my EHD fail within months of each other! I lost some photos and MANY MANY kits (it was my downloads EHD not my photos one). Since then, everything is backed up on 2 EHDs and I try to keep my laptop to just the most recent things.