Split BIP39 words by hand
Best practice is not to split up your seed words.
There are many different clever ways one can store their bitcoin back-ups and the way you described might be one of those ways. It may work for you and that's great, but it isn't an approach that would be generally recommended or accepted.

The aim is to store the word list in several locations

Generally, it is recommended to use multisig if you want to split up any sensitive data that will be used to sign a transaction.
Alternatively, you can add a BIP39 passphrase that could be stored separately from your seed words.