I used to do this constantly but I had to break myself out of the habit. On long drives, I’d forget I would have passengers and blurt out half a sentence before realizing.

It also led my step mother to try and convince my dad I was schizophrenic at the time since I would do it in the house as well when I thought no one was around.

Mildly annoying since it was just an easy way to think things through, I never saw it as a bad habit.