The only way to ensure purity in the final decision is to eliminate any source of bias, especially subjective preference. Decisions based on hierarchy, history, ties, and sympathy are removed during the process.
Making sure that the method is executed in every step of the process confers confidence in the final decision and minimizes the risk in future implementations. Guidelines, policies, and rules are there for a reason, and no exceptions are made.
You’d be surprised how easy it becomes to separate the wheat from the chaff.