When I won a cryptosteel in a raffle here on the forum, I learned that all I needed was the initial 4 letters and everything would be fine
It wasn't until I used it and was sure it worked that I was reassured and learned more about the BIP39 in that sense
A healthy habit I now have is to check the seed immediately after backing it up somewhere. On my airgapped computer I do a simulation by restoring the wallet using the backup and checking if the addresses match. This way I am ensured that if I ever really need to restore my wallet, it will work.
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It's your last checking time, to verify validity of your wallet backup. If this last checking round gives you a same wallet as your initital wallet, it shows you that your backups are valid and usable for wallet recovery.
You can end here, sleep well and don't worry that in future if you need to recover your wallet, you will end with a wrong wallet by an invalid backup.
I only just saw this after writing the reply to rdluffy. Yes! This is great practice and the best way to verify whether the addresses are the same. Although being so paranoid does not always help. By inserting more checks and verification I only become more paranoid of making a mistake, forgetting something, doing too much, creating vulnerabilities et cetera.
If I had no airgapped computer I would probably never even do the final seed check, it would scare me knowing I manually typed down the seed into a computer connected to the outside world.