Most Damaging Avoidable Mistake for First-Time Festival Strategy?

Hey everyone, Rohan Kapoor here, working as a cinematographer, but venturing into my own short film as a director/DP. We just finished grading our 15-minute drama and I'm starting to look ahead at festival submissions. I've been poring over various articles and conversations about festival strategy, and a few common red flags keep popping up, things like the 'spray and pray' submission method, or the absolute necessity of good sound. While these are clearly critical, they often feel like foundational 'best practices' rather than specific strategic errors.

My team put a lot of effort into sound design and a focused submission list, but I'm worried about missing a less obvious, yet equally detrimental pitfall. From your experience, what's the single most damaging but avoidable mistake a first-time filmmaker makes in their festival strategy that isn't just about general technical quality or a scattershot approach?