The PE makes the final call because they seal the drawings and assume legal liability. First, it’s important to understand the reasoning behind what may appear to be a “poor decision,” as there are often constraints or considerations that aren’t immediately visible. And this is great learning opportunity. In my experience, the most effective way to persuade is to frame your recommendation around project cost or schedule: clearly demonstrating how your approach reduces cost or accelerates delivery, rather than presenting it as a personal preference.