In this scheme one back-up can be lost and funds still retrievable, so it's like a quasi 3-of-4.
I am considering an upgrade to a 2-of-3 multisig:
location #1: Seed #1 + xPub quorum
location #2: Seed #2 + xPub quorum
location #3: Seed #3 + xPub quorum
digital: Various xPub backups
The main advantages of 2-of-3 in my case would be that it's more resilaint against evil maid attacks (as multiple devices need to be compromised), and I'd be unable to forfeit the keys while under duress (as nothing is memorised).
The main disadvantages of 2-of-3 in my case are complexity and potentially privacy (as the xPub quorum reveals one's balance).
I go back and forth on the decision to upgrade. I think SS+P is fine for now, but at some point we may be living in a more adverserial environment where KYC data is leaked and BTC is worth x10 today's price. I would certainly appreciate the extra security in such a scenario.
MicroSD with encrypted seed backup (7zip, AES-256) - generated from Coldcard, protected by 12 words, never to be inserted into anything other than Coldcard, or Tails (in case of emergency)
Coldcard Mk4
Passphrase (six BIP-39 words):
Keeping in memory
DIY Stainless Steel Washers
Password manager, archived and stored under random name
KeePassXC vault inside of a Cryptomator vault stored in multiple cloud services and local flash drives
Standard Notes protected note
12 words for encrypted backups
KeePassXC vault stored in multiple cloud services (different from ones storing the passphrase)
I keep separate accounts for KYC, "Light" KYC, and P2P No KYC.
All other wallets are derived using BIP-85 from seed+passphrase as a master parent seed.
All online services are protected by YubiKeys or YubiKey Authenticator 2FA TOTP codes and very strong diceware master passwords.
Not ideal, probably too many backups, but I'm still learning. Will be moving to multi-vendor 2-of-3 or 3-of-5 multisig in the future, when I get more comfortable with it. And I should probably delete this comment soon.
The best way is to post your 12/24 seed words on social media ..... Everyone will think its a scam or a joke so they wont do anything ... and one day u will dig for that to access your BTC
Seed backup:
Passphrase (six BIP-39 words):
12 words for encrypted backups