In my opinion, you have created a good storage system for your bitcoins.
As far as I understand, you have three wallets, each of which has its own Seed - phrase?
If so, it seems appropriate to memorize these three Seed phrases. You can remember seed phrases using mnemonic techniques.
In particular, there is a popular mnemonic technique for remembering important information called Mind Halls. However, it is described in detail in the series about Sherlock Holmes.
Memorising 3 seed phrases is extremely difficult and is susceptible to errors. In my opinion nobody should trust their memory for long periods of time. Memory is good, but unfortunately, you can't manage what you remember.
The plan is great. Especially that you have kept two backups of the seedphrase so that just in case one of them goes missing or destroyed you have the other one to rescue. Also keeping 60% in a cold wallet which is not connected to any web is a great idea as well because the biggest chunk of your portfolio is then perfectly secure without any harm from hackers and even far away from you that you sell it in panic.
Thank you!!!
First layer wallet - 20%
Second layer - 30%
Third layer - 50%
This is what im doing similar to yours on which i do make out partition on my coins and this isnt only limited on Bitcoin but also
into other altcoins as well on which i do make out that kind of dividing so that i wont really be losing it all once i would be hacked or some exploit or do make out some mistakes.
It wont really be that hurting that much if ever there's some accident since we know that internet connected devices are really that always prone to these things.
In general, cryptography is a complicated subject. It makes you suspicious, not trusting anyone/anything. I love it for this reason.