Does MAP adjuster work at part throttle

Will a MAP adjuster adjust the fuel delivery during part throttle applications as well at WOT? If it does adjust during part throttle doesn't this throw off the 02 sensor readings causing the ECU to adjust it back to normal?

The MAP adjuster works under all load conditions, not just at WOT, so even under part throttle the MAP sensor signal plays a major role in determining the A/F mixture.
When the ECU is in closed-loop mode (deceleration, light throttle cruise), it uses the O2 sensor as its primary signal for setting the A/F mixture instead of the MAP sensor so whatever signal it gets from the MAP sensor, the ECU will use the O2 sensor reading to correct the A/F mixture to stoichiometric.
Under open-loop operation (acceleration, warm-up), the ECU uses the MAP sensor signal as its primary input for setting the A/F mixture and the O2 sensor signal is ignored.