No general rule applies in Germany.
I find the idea of "general rules" totally ridiculous anyway.
What is done or not is the decision of the people who have the relationship, and NO ONE ELSE, period!

Of course there is the Wannabe/D-s/both fraction who tells everyone their opinion, especially if no one asked them to do so.

It has been - oh see the significance - here in chat that a German "Domme" gave me the lengthy, highly boring "but as a sub you should have smallcaps and your Domīs name in this collar-bracket thing" etc. speech.

What I can say for Germans is that the majority I met in the BDSM area apparently LOVE to be tiresome, boring, tedious, patronizing, judgemental, intolerant, unbearable know-it-alls.
This is also the case in the German online forums, which is the reason why I so hugely enjoy being here!

End of rant, thanks for listening.

As for my Dom and me: He would fall over laughing if I addressed him as "Sie"/formal, yet he is the best Dom I ever met. He is strong enough to let me be me, and does not expect me to be a doormat.