I'm currently getting into veracrypt based cold storage, ie keeping private keys in a veracrypt container and making multiple backups to offline devices. My next step for long-holds with be burying some copies of these USBs, as I really like the idea of burying your crypto gold for the future. Incase your house burns down or you are robbed for example, always have at least a dozen backups is what I say, most importantly some that are extremely inaccessible.