What does this do? I couldn't find anything in the Warpedia about it...but since it exists, it must provide some sort of advantage...just trying to figure out what I'm missing out on by not doing this at all.
It removes them from the queue of units you cycle through with the "Next unit" button. So it's an extremely useful time-saver. Using the buttons in the right-hand movement toolbar as intended insures efficient use of time and prevents you from missing units that have movement left.