The problem arises when there are new versions of existing ISOs to be copied. I delete the old versions and run the same script with xcopy /d so unchanged ISOs are untouched. The new ISOs are likely to be larger and maybe trigger fragmentation. Rebuilding the key from scratch or booting and seeing if there are complaints about fragmentation are both time consuming. I'd like to know as soon as possible if I have to fix the key. It's worse these days because I'm working from home and passing the updates to someone who is in the office and has no experience with making bootable keys.