Rookie Mistakes in Writer's Deliverables: What Scares Off Greenlighters?

Hey everyone, Marcus Johnson here. I'm working on a few different projects right now, a feature script, a pilot, and a short I'm hoping to direct myself. As I'm putting together pitch decks, synopses, and even just simple outlines, I keep wondering about common pitfalls. Thinking back to when you were starting out, what were the most frequent mistakes you (or others you've seen) made when crafting these 'writer's deliverables'? I'm talking about anything from pitch materials to a basic synopsis. Were there any blunders that nearly cost you a greenlight, or delays that almost sank a project before it even got off the ground? What did you learn from those experiences that you now consider essential for getting it right?