They wouldn't count each frame individually, as that's not how it's done - they'll have "guide feathers" which are manually keyframe animated, and the feathers

They wouldn't count each frame individually, as that's not how it's done - they'll have "guide feathers" which are manually keyframe animated, and the feathers in-between are interpolated from the guide feathers (which is how hair/fur is done). Per frame this just results in different positions/shapes for the curve primitives which make up the feathers.