hopefully only the nice ones!... I'll be on the lookout for your typos!!
What "it" are you talking about?
Kind Regards, John
I believe number 3 with L&N both appearing at both switches is still practiced in USA if one of the YT videos I saw a little while ago is valid.
It used to be popular for outside lighting between buildings, for example farms, where a light mid way between buildings only required one wire from each end.