I found the Driftveil and Marvelous Bridges more of a help than just a Ducklett/Swanna nest. The wings you can find, save the Pretty Wing, while appearing useless, sell for 1500 PokeDollars! They're so common, and so pricey. I'd say it takes about 10 min. to collect 20 or so of each wing with minimum Swanna/Ducklett. Well?
~AoH
~AoH