Engineering mode is only for lab testing and in the field the chip will be in Smooth mode. In Engineering mode, the RFIN AGC will never change unless you perform a reset.
In Smooth Mode, PA gain variation or temperature variation would cause the RFIN AGC value to be adjusted, so this won’t happen very frequently.
For both Engineering and Smooth mode, the RFFB AGC is adjusted when the PA output power change. So this should change more frequently.