1.4.3 Natural justice is about the process, not the decision
The purpose behind natural justice is to ensure that decision making is fair and reasonable. It is important not to confuse those objectives with what is legally required. Determining whether a decision complies with natural justice will generally depend on whether a fair and proper procedure was followed in making it.
A common outcome of judicial review is that the review body sends the decision back to the decision maker to make again using due process. That is, successful judicial review will not typically result in the review body substituting its own decision (though it can do so).