Actually this is not Shamir's secret sharing.

Here's another quote from one of the referenced posts (https://bitcoin.stackexchange.com/questions/107380/why-is-it-bad-to-split-up-a-wallet-seed-redundantly):

"I create a wallet with a 24 word seed. I don't use Shamir's secret sharing algorithm, because I see this is widely advised against (see for example this article) and is a potential source of risk from cryptography I don't fully understand. Instead, I use a naive scheme I can perform entirely by hand where for each group of three words in the seed, I split them up like this:

Location A  Location B  Location C
word 1      word 1      	
word 2                  word 2
            word 3      word 3

So each of the three locations has 2/3 of the words, i.e. 16 words. It's easy to confirm (by experiment, if necessary) that I can reconstruct the full seed from any two of the three locations.