Turn signal is a "I see the space I'm gonna merge into, this is my warning to you that if you speed up and close that gap out of spite, I'm going fast enough to make this merge that we're both gonna have a bad time" signal for me. Like, when merging onto a highway, turn signal comes on when I'm lined up with the space I'm merging into and gonna make the move in a few seconds.

I try to make space for people that are just humming along with their signal on trying to find a space to merge into, but 9 times out of 10 it's just some fucking schmuck who forgot to turn it off and I just made traffic worse for everyone behind me for no reason.