Mr and Mrs.T....
I believe if one does it properly from good micro to good farm design and from choosing the right Aroma to right Sound to get a few thousand nests in a short period of time is not impossible.
In the above case Mr and Mrs.T had proven it again good Aroma and sound are vital. Never a afraid of changing Swiftlet farm's sounds the only fear is that you might have changed the wrong sound. It means you may have bought the wrong sound from people you believe is professional but there are not.
Good Swiftlet farming All!