I would recommend getting an actual duster (aka "hand bellows"), especially one that has an actual spring to return the bellows instead of just a "plastic spring". I learned it from this video [0].
It really helped to basically make the dust small enough for the roaches to scurry through (instead of avoid like a pile). They don't really want to eat it (like bait), so they need to accidentally walk through it and then clean themselves (and incidentally ingest it).