7D and lenses effecting cross over focus points?

I’m rather embarrassed to admit that I’d never really thought this through before.  This implies that when the selected lens aperture is smaller than its widest aperture and the camera is in AI Servo, the lens’ diaphragm, a mechanical not electronic mechanism, is opening and stopping down again at up to 8 times per second.  Is that correct?  That’s really quite remarkable and would help to explain the high cost of lenses.

Peter