Each other VS One another

You may probably have come across a situation wherein you kept asking yourself whether each other or one another.

Well, as far as I'm concerned, each other should be used when we know the number of items / persons in question, usually a low number.

Marcos and Eliane met each other last month. (2 persons)

But

They were at a party where people didn't know one another. (unknown number of people)

Besides it, I've already seen a more simplistic explanation stating that one another is the preferred choice when we have more than two choices.

Perhaps, another explanation would be where the focus is given, if you want to emphasize and give focus on the individuals or not. In case the individuals do not matter, if you just want to be informative of the situation, my feeling would lead me to choosing one another. Conversely, each other.

I keep on using it according to my knowledge of the number of choices involved. If the number is known to me, I use each other; rather, I opt for one another.

Do you have an opinion on it? Let us know!