Hardware doesn't have an indefinite shelf life either. Are people also keeping engravings & whatnot as ultimate backup?
But seriously, write down the 12 seed words, keep it somewhere safe. Make another copy, tear it in half (6 words each) and keep one with a relative and one at work. Check them at 1, 2, 4, then every 6 months.
But for most people this is all overkill: just use a mobile wallet.
This isn't a good idea; every word an attacker knows makes the remaining words exponentially easier to brute force. if you're going to split your key into pieces, you should use something like https://linux.die.net/man/1/ssss