Authors don't know whether to include their full manuscript in book proposals, causing rejection and wasted effort

Aspiring authors struggle with the ambiguous, contradictory guidance on book proposal formatting—specifically whether to include the complete manuscript or just sample chapters. This uncertainty leads to rejected proposals, missed publishing opportunities, and wasted months of work. Current solutions (agent websites, publishing guides) provide conflicting advice that varies by publisher and genre, leaving authors paralyzed and unable to move forward confidently.