I have gotten my U2's beak trimmed just once, about eight months ago. I haven't done it since because a very reputable breeder said it was unnecessary and felt to the bird like somebody putting a drill on our teeth.
Please someone correct me if I'm wrong but it's my understanding that you shouldn't ever have to trim your parrot's beak if you give them plenty of hard things to chew on to wear it down. Even the act of eating seeds helps a little.
Beak Trimming should only be completed by an Avian Professional, like a CAV or a CAVT. The nerve mass at the base of the upper Beak is highly sensitive. Over trimming is common when the work is done by the uneducated. This commonly results in the Parrot not being comfortable eating. And, that can turn into a serious problem quickly.
That all said, as part of understanding plucking, it has been found that removing the point of the upper Beak can reduce irritation of the skin and in 'some' Parrots, reduce plucking.
Over-growth is more commonly an issue of diet /illness. Then followed by limited use of the Beak. Your first (very soon, after bring the Parrot home) Well Parrot Avian Vet Exam should include that discussion. If your Parrot's Beak is overgrown, the recommended full blood screen should provide indications as to what direction you need to proceed.