Honestly a not-the-worst back-up for a starter is just regularly (monthly for example) plugging in an external SSD, HDD or even a memory stick and put data you value in cold storage. Almost all can be rebuilt and gathered again, except data you personally value.
More important than ratio is how many seeds are left. Keep the ones that are low on seeds, ditch the ones where there are hundreds of others seeding.
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Your local library can be an awesome source for audiobooks. And don’t forget to check your local thrift stores and flohmärkte once in a while, many audiobooks for 1 - 2 €, also many recent ones… Rip it, put it on your audiobookshelf, it is very easy and fast for most audiobooks.
I think because it lets them see themselves as scientists or so