I don't have actual conversations in my head but sometimes I think about some of the opinions that I have and compare them to what other people's opinions might be and I try to figure out the conclusion of the differing opinions when put against eachother.
This is mostly due to the fact that I try to express my opinions online and expect to get replies but many times I don't get the discussion I am looking for so I improvise a potential counter-argument to mine so I can have a productive dialogue in the subject I want to talk about alone.
I feel it helps me grow as a person and my debating skills improve on its own.