yeah you can do this on emails. make three different emails.
say 24aatyb6531@yahoo
and zz2266tak12@yahoo
and tw24xtyuoks@yahoo
put eight seeds in each in each address.
I would advise against it!
If you have absolutely no other solution, at least make it more difficult, four different addresses with different phone numbers (use a prepaid card) and spread the seed between those, not an entire seed in one address because if you do that and it gets hacked you've lost it, if you spread it then the hacked will only get 25% or 33% of the seed which would be useless!
Ignoring the small cases with users getting their google account hacked and their seed phrases stolen, we have the Mixin case where 200 million were lost because of a breach that led to their cloud storage account getting compromised!
Nice idea. Backup phrases with brain memory are very effective,
They are not!
People are not machines, they are bad at randomizing and are bad at learning and memorizing random stuff.
We use most of the time a mind picture or a logic chain to memorize things, if you can't find one in a series of 12 or 24 words most likely you will forget it unless you practice that thing every day which kind of defeats the whole thing!
There were numerous experiments with how people memorize things and excluding elements from memory is normal, so translating this to bitcoin seed phrases, if you happen to have a thing like:
cabbage grape jealous banana
your brain will try to associate the three words that are vegetables and fruits which would lead overtime with losing the 3rd word in the sequence.