Instead of try to do what can make you to lose your seed phrase, why do you not use passphrase with the seed phrase? You can read about passphrase and it gives your coin additional security.

But know that if you forget the passphrase, you will lose your coins.

Backup the seed phrase and passphrase in different locations. You can have like two or three backup of each. You can do the backup on paper or steel or stainless steel sheets.

Stupid idea.

Because if he lost two words of his seed, it the rest 10 or 22 words will be useless. He will have to use service to brute force it and if brute force does not work, he loses his bitcoin. Spliting it does not make it more secured but worse. What will happen if one of two words are from checksum?

Why is Seed Splitting a Bad Idea?
How to back up a seed phrase?

Yes it can be a key security solution. But are you sure you won't forget those 2 separate words? Maybe you can also save 12 of the 24 words in a different place. I think whatever you do will be good for you as long as no one finds out about your plans.

So it's better if you do what you plan to do without sharing it here, so what you keep secret will be completely safe. But for stronger security, maybe you can consider using a multisign wallet. You can store keys in separate places and can share keys (10 of 12 words/ 20 of 24 words). Especially if you plan to hold bitcoins for a long time, multisign is the best. It can be a family asset and you can give keys to each family member to make it more secure

I think it's a good way to save a phrase, but only if the person is sure enough that the remaining phrase won't go off his head. Those 10, or 20 written-down phrases on a piece of paper will be kept safe out of the reach of others, and even if there is any chance that someone will come into contact with those phrases, they won't be able to access the wallet because of the other missing words.
 
I can remember a guy back then whose wallet had a private key, and among the 64 characters, the guy had four of them removed from different places, not just at the end or beginning of the wallet. This makes everything very complicated; he removed those words and stored them in his memory, and the rest of the key is stored in his email, where he can access it wherever he is. This makes the wallet security strong to me, because in such situations, even if one is given those four missing characters without knowing where they properly belong, you won't be able to access that particular wallet.

There are many ways to store seed phrases, and each individual has their own method.  we shouldn't judge someone else's method as bad just because it doesn't work for us.  It might not work or give you security, but for that guy, it's for the best for him. in my opinion, store your seed phrase your way, you don't have to imitate someone, whatever the method, as long as you feel safe with it.

This is not that bad when he has strong memory because he will gonna keep that seed phrases for years and when he doesn't review everything every 2 months in minimum, then I absolutely believe that he will gonna forget everything. The best thing to do is whenever you want to hide it in multiple places by dividing the total words, you need to appoint a schedule where you will gonna review everything or place them in different places in order to secure it. Some people don't really need to do this because they memorized their seeds but others need to do it because they don't have strong memories to remember.

it is good idea but risky one, may the 10 words written on the paper get destroyed or get lost?

here's my idea very similar to this.

you can write 10 words on you steal or metal door or steel sheets and you need to store that remaining 2 words in very secret place or very securely. or repeat those 2 words every morning. so those words get stuck in your head

I don't that that there is any need for doing something like that because it's always preferable to store your whole seed words in a single text file and save that file on multiple storage devices, and then disconnect all those storages devices from internet. With that simple step our seed phrase and our private key gets the top level of security because no one else can access those other than we ourselves.

I must say that his idea isn't great at all because why take a lot of burden if you can follow the easy path which has already been tested and is currently the most secure and trusted method to keep ones private keys or seeds words without any worries. I think it's always safe to go with the tested method which I have already explained because that method can't be hacked with current GPU's or any other hacking methods.

The most problematic thing that can happen with such idea is brute-force attacks because if someone knows 10 words out of 12 words or 20 words out of 24 words then that person can easily brute-force that wallet and gain access to it. Brute-forcing of 2 words isn't hard these days thanks to powerful GPU's, and even 4 words isn't that much trouble causing for someone who has cluster of those powerful GPU's.

Don't try to make your own system when there already are working mechanisms of storing seed words.
The most basic one includes multiple copies of all seed words in multiple geographical locations. If you want more security, set up a passphrase and store it separately from your seed. Obviously, you should have several backups of both. Finally, you can create a multisig setup made up of different devices that hold the keys. Preferably, an airgapped computer, a paper wallet, and an online machine or mobile wallet.     

I believe that when it comes to storing coins, people should not merely rely on public opinion, but also on what they know about themselves. I know that my memory is average, but not reliable enough that I'd trust it to not forget a passphrase. I know that I never take my laptop outside my flat, and that a chance of my particular flat being robbed is pretty small. I also know that I'm way more likely to forget where I put that second piece of paper with the two remaining words than be compromised because of downloading malware or something like that. So based on that, I wouldn't separate the passphrase storage into two places, but that doesn't mean it's the right decision for everyone.