You're absolutely right splitting of seed phrase in multiple parts sometimes you might lose one part, I think is advisable to have the seed phrase all joined together in a hidden place, so as to avoid losing your seed phrase however,I don't split my seed phrase rather i put it in a very hidden place.
It's not advisable to split a seedphrase into two parts or more, if you want to have a protected backup, it's safer and more reliable to extend these words (passphrase) where the seedphrase is something you have and the passphrase is something you know.
Their is no need of splting the seedphrase and keeping it in a different location because sometimes things occur that you can just forget or something happens which you won't be able to get access to it. I believe when a seedphrase is being taking care of very well and placed in a secure place it is safe, but splitting it in a different location I think you will have a lot of works to do to make sure you don't forget these location.
Having the complete seedphrase in same location is even more safe than having it different location. Sometimes we may be thinking we are trying to give the best security but instead just making things very complicated.
I believe as an investor many don't have just one wallet, people do have several wallets. Just imagine all the seedphrase of these wallets are splitted and kept in a different place, don't you think if you are not very careful it can be very confusing by missing everything up. Store your wallet seedphrase that will be simple for you but very difficult for other people to get access to it.