Are you guys not double-checking it? Or even try to re restore it; let's say the wallet is already set up. Before funding it, try to remove that wallet first and restore using the words you just wrote.
Last time I set up my wallet, I did and so far so good.
This is for sure commno problem, there are some Bitcoin wallets after backing it up, they will ask you again to enter so they are sure what you wrote are all correct.

Backing up your seed phrase may just be a normal routine, but a slight oversight could be costly, very costly. I once wrote down my seed phrases and put the paper safely away. Months later, my laptop had an issue and I tried using the seedphrase to recover my wallet but couldn't. All efforts to import the old wallet didn't work, so I decided to take a closer look at the seed phrases I wrote down. I was struck with horror when I counted them and they were eleven words instead of twelve.

I wondered how I missed a word, a seed.

Days later after fixing my laptop, I accessed the wallet and quickly checked up the seed phrase. The issue was that I misses a word that was consecutively repeated. It was like:

milk honey truffles anger woman kings seed seed bananas oranges action event


It completely eluded me that a seed was repeated.

It could have been worse.

Have you made a mistake such as this?

For many, the seed phrase may seem simple, but it is not at all a simple matter, rather it is the most important thing. There are many people who carefully save their seed phrases and try to keep them in a safe place, while there are many who avoid them and face danger at some point. The mistake you made was definitely a big mistake. If your laptop had completely crashed due to a mechanical fault, your money would have been lost. So, this happening to you is definitely a warning sign. We should always pay attention to such things and save them well.

Personally i haven’t made such mistake but i know its possible to make such mistake, the seed phrase has numerous words that are obviously very difficult to cram, the only way of saving it is by writing it down properly and also backing it up, what i did was to write them down and archive within my core valuables, i also had duplicate copies that are well safeguarded because any mistake that results in you losing your seed phrase just know that you can’t access your crypto wallet again.

It's not hard to write the wallet seed phrase down accurately, and it's a requested step by Bitcoin wallet softwares too, so people actually do their wallet backups. It's only they will whether keep that wallet backup safely, make some copies, or just have only one wallet backup to use in the future. Some people throw their wallet backup arbitrarily then later they lose it, or they do not mind to store it.

It's not recommended wallet backups but people can learn about that, and they are all able to do that rightly.

Errors will certainly occur due to habit, and we assume it's normal because we've done it so often. However, careful cross-checking is also essential. If the balance is small, it's okay; if it's large, you might have to look for one more word to complete it.

Have you made a mistake such as this?