I agree with the need to have an offsite backup, but only having this backup still leaves a realistic possibility of data loss. You will typically leave it unattended at the bank for years and only try to access it when you lose access to your wallet. At that point there is a possibility that you find out that the backup can be corrupted (if it is on an usb drive) or is otherwise inaccessible.
Generally the best practice for backups of personal data is the "3-2-1 rule" where you have:
  • 3 copies (one of which may be the wallet file on your hardware wallet or computer)
  • with 2 copies on different media (could be seed plates)
  • of which 1 copy is off site.
That way if either your onsite or offsite backup is corrupted or inaccessible the other backup copy is still likely to be valid and accessible. So basically I would say to both keep a backup at home and one offsite in a safe at a bank.
If for some reason you don't feel safe using a seed plate you can also use an encrypted usb drive or multisig, but there are caveats there. Your seed should -never- touch a system that is online, so you need to use something like TailsOS to make the encrypted usb. Also a very real risk is that you lock yourself out of the backup, so you should only use these if you are comfortable working with them (keep it simple stupid).
Also practice restoring your wallets from backups on a regular basis to make sure it works as expected.
In general I feel that making safe and secure backups of your seed phrase is the most challenging part of using bitcoin, so please let me know if I am missing something.
Yeah, the "3-2-1 rule" is probably the easiest to explain to an inexperienced user.
I think the seed plate stuff is overemphasized in the Bitcoin community. 3x paper backups (home, bank box, and family/friends's house) is enough for anything other than an extreme edge case. Your house isn't going to burn down, at the same time your parents' house gets hit by a tornado, at the same time your bank floods.
And I thought about recommending an air gap computer solution, since it's so useful for verifying keys, generating seeds, and additional encryption. But I think it's too much for a noob guide like OP is making. Too many places to mess up and the message should be simply "never put these seed words into an phone/computer!"
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