Welcome to the community!
What is your optimization target? Operational cost, development cost, speed, or accuracy?
100% accuracy is almost impossible.
Here’s a potential problem with “megaprompts”
One cause of inaccuracies is context confusion. This happens when you have a long context that contains many similar passages. If you put multiple products into your context (prompt) and they are structured fairly similarly, it’s possible that the model “looks” at the wrong passage when generating a response. To prevent this from happening, it’s a good idea to elide everything that is not relevant to the current user interaction.