I often insert a please and thank you into my responses. Though I do so for practical reasons.

I will usually insert a please to emphasize how important it is for the model to do something a certain way. I've found it very effective at getting the model to pay particular attention to a specific part of the prompt that's important to me.

Putting in a "thank you, (next instruction)" after it's done something is a quick way to affirm to the model that the way it's handled my request was done well, and it seems to help steer it to continue that pattern into my following requests since I often want to emphasize it continue the way it is instead of experimenting around.