When I was learning to drive, the government issued pamphlet included a phrase similar to, “Always use your signals, the car you don’t see is most likely to be the one that hits you.”
So I use my signals for any turn, any lane shift, no matter the context, no matter where I’m driving.
When I was carpooling to work a long time ago, a friend gave me some friendly grief over my usage of turn signals within an apartment complex’s parking lot. “Why are you using your signal? There’s nobody here.”
“Because the car I DON’T see is the one most likely to hit me.”
“But there’s nobody here.”
“Nobody that you see, but what about the car you don’t see?”
This is a rerun, and the fediverse is better