I have a locker at my place of work where I store a few HDDs and USBs. These are the most up to date, but I also have others at my parents place and my in-laws. Gets troublesome keeping track of which ones are up to date as of what date. Good challenge for staying organised though, I've got a whole naming system and numbered hierarchy and scripts that run ordered by priority.
Well overdue for a refresh.
I use a similar system. I have paper console tape on each drive and write the date last used on it and also keep a text file log of which drive and when. The backup batch file also writes a timestamp.txt to the root of the drive.
I also have a set I curate and put in with the family & household papers. That doesn't have any of my personal crap, just documents, photos, and family history etc.
I think there is a system to do this with git (maybe git ostree or annex) that will just keep the hash link in a repo but have the file in a offline drive, so you can easily keep track of files that are in cold storage. It may need you to have your own encryption system though.
I do this too, but with ZFS. So, since the snapshots have the creation timestamp in their name, it's obvious which drive has the latest data. But I also tend to remember if I went to the office or to my parents' house last.