People can often be observed to be deliberately making an effort in casual, social, natural language conversation. It flows for some people more than others. Try watching Big Bang Theory and see characters at times being deliberate with their words and at other times responding automatically.
An LLM can do increasingly well as a fly on the wall, but it’s common for people using an LLM to be less collaborative with an LLM and for them to expect the LLM to structure the conversation. Hence the suggestion to be careful in your prompting.