On occasion I'll signal early, then realize that my signal could be interpreted as ambiguous, turning into either a major driveway, or into the next road coming up. Sometimes I'll turn off the blinkers until I pass the driveway then turn them back on.
I can also imagine people slowing down and signaling, then either changing their mind on where they're going, or realizing they have the wrong road. Thus, turning off the blinkers, and accelerating back to their normal driving speed. Perhaps one is new to the area and just slowing down to read the street signs.