Yes, a trio will feed a small family pretty easily. If I cook one duck a week, that's only 52 ducks needed for an entire year. A trio will lay many more than 52 eggs in a year. If I wanted to keep the incubator running, I could probably hatch out 300 ducklings from a trio of ducks. Thinking of it in those terms, a trio should be enough to put duck on the table every night of the entire year. I just don't want to eat that much duck.
I did the math. I have to hatch out more than 25 ducklings to make it pay. If I want fewer than 25 ducklings, it is cheaper to buy them and not keep breeding stock.
Much as I like duck, once a week is more than enough. I have geese to eat, and we will be raising some Cornish Cross chickens, and then there are a lot of eggs to eat, so some meals are omelets or other egg based dishes. Some of the Appleyards and Swedish end up on the table, too. On top of that, the veggie garden and orchard produce a lot of food that needs to be eaten. (Yum, duck and asparagus stir fry!)