I agree with Anna, Linda, and Margaret. I have had my little Jacques for a year now and we were told we had to have her beak trimmed every time her nails were done. I had never heard of this and wanted to do some research before I said yes. Good thing I did. If you start typing "exotic bird beak trim" into Google and modify it from there you can find out some interesting things. For me, it broke down into some birds need it done if they have underlying health issues like fatty liver disease, otherwise a good sandy perch is good enough. Also like Margaret said, there is a sensory organ located near the tip that can be irreperably damaged by an improper beak trim.
Since I have had Jacques as well as our 4 other fids (Nanday, 2 male Ekkies, Sun Conure, and Dusky Conure) we have not had to trim nails or beaks as long as we have a sandy perch by the feeding stations:)
Carrie and the Crew