My question here is, if you are on the interstate and are in a lane that exits completely - the lane itself turns off and the road is left with one less lane - do you need to use turn signal?
I guess it partly depends on how you define “need”, and I’m actually unaware of what the law says in the matter, but I think it’s definitely a good idea. It lets other drivers know that you are being attentative and exiting (as opposed to being unattentative and in the wrong lane, and have to jump back over at the last minute).
Virginia does not require a signal when changing lanes (amazingly). But in a state that does require it, in the case you describe you are not changing lanes and a signal would not be required by law.
I otherwise agree with Cabbage.
However, you need to check TN’s laws on the specifics, they might require a signal when leaving a highway or some such thing. Every state’s different.
I’m a habitual turn-signal user so I would be using mine.