I feed my ducks twice a day in the same spot not too far from their duck house. Now that I've done this for about a year, the flock comes running to me at breakfast and dinner time (which happens to be when I get home from work). After dinner (around dusk), they know to meander to their house for the night. After a year or so, they know the routine and they nearly do this on their own with minimal encouragement. They also know the sound of the lid coming off the top of their food container and come running.
I don't know how this happened, but when I yell "Where's them ducks?", they make a quack racket!
Enjoy,
Rich