Refrain from committing to a solution early (a.k.a. Don’t get married to a solution): You already know this one but it’s easier said than done. Most aversion from designers, when faced with critical feedback, comes due to the amount of effort it takes to make large-scale fundamental changes to designs in advanced stages of a project. One way to circumvent this trap of Sunk Cost Fallacy is to set up your own malleable design system that helps you iterate quickly and iterate a lot — for me this has been a Sketch template with a collection of nested symbols (it helps me multiply a small effort into large and quick variations in designs that help propagate a discussion). When you explicitly make an effort to remain preoccupied with the problem by not seeking quick closure with the next reasonable solution you find, you increase your odds of coming up with a more formidable outcome.