I used to write to DVD's, but the failure rate was astronomical - like 50% after 5 years, some with physical separation of the silvering. Plus today they're so relatively small they're not worth using.

I've gone through many iterations and currently my home setup is this:

• I have several systems that make daily backups from various computers and save them onto a hard drive inside one of my servers.
• That server has an external hard drive attached to it controlled by a wifi plug controlled by home assistant.
• Once a month, a scheduled task wakes up that external hdd and copies the contents of the online backup directory onto it. It then turns it off again and emails me "Oi, minion. Backups complete, swap them out". That takes five minutes.
• Then I take the usb disk and put it in my safe, removing the oldest of 3 (the classic, grandfather, father, son rotation) from there and putting that back on the server for next time.
• Once a year, I turn the oldest HDD into an "Annual backup", replacing it with a new one. That stops the disks expiring from old age at the same time, and annual backups aren't usually that valuable.

Having the hdd's in the safe means that total failure/ransomware takes, at most, a month's worth. I can survive that. The safe is also fireproof and in another building to the server.

This sort of thing doesn't need to be high capacity HDDs either - USB drives and micro-SD cards are very capable now. If you're limited on physical space and don't mind slower write times (which when automating is generally ok), the microSd's and clear labelling is just as good. You're not going to kill them through excessive writes for decades.

I also have a bunch of other stuff that is not critical - media files, music. None of that is unique and can be replaced. All of that is backed to a secondary "live" directory on the same pc - mostly in case of my incompetence in deleting something I actually wanted. But none of that is essential - I think it's important to be clear about what you "must save" and what is "nice to save"

The clear thing is to sit back and work out a system that is right for you. And it always, ALWAYS should be as automated as you can make it - humans are lazy sods and easily justify not doing stuff. Computers are great and remembering to do repetitive tasks, so use that.

Include checks to ensure the backed up data is both what you expected it to be, and recoverable - so include a calendar reminder to actually /read/ from a backup drive once or twice a year.