Hi! I'm going to hazard a response, although I am not the most educated sub out there- still fairly new. I think that there's a certain level of formality that most Doms expect when you are speaking to them, and it is somewhat similar to how you would speak to someone in authority of a great importance. Often they want you to refer to them as Sir, or Master, or Daddy, or some other term of respect. Different Doms will have different ideas about how formal they want your speech to be, and in what circumstances each level of formality is appropriate.

Personally, my Master allows me to take a somewhat more casual tone at times if we are talking about light matters- but I must always be able to quickly take a very formal and respectful tone if needed. I think the best way to learn what is expected is to ask your Master about it because different people will have different ideas on the topic. He may be able to provide guidance for you in the way that he desires.

Good luck in your learning experiences!!