I got a cockatiel that was already clipped. The breeder cut 10 flight feathers from each side, so it is 20 flight feathers! I usually hear people normally trim/cut 3 or 4 flight feathers from each side. Total of 20 seems too much. One day, she fell from my hand while she was flapping/ exercising her wings. She landed on the door mat, but the impact of a fall actually cut her blow chest. The cut was one inch deep. So extra be careful with the clipped bird.