A toothpaste factory faced a challenge: they occasionally shipped empty boxes without the tube inside. This issue arose due to the production line setup. Designing precise production lines is complex, requiring quality assurance checks strategically placed to ensure every unit is flawless. To address this, the CEO initiated a project with an external engineering firm to tackle the problem. The project, involving high-tech scales to detect underweight boxes, seemed successful with no defects reported. However, upon investigation, it was discovered that a simple desk fan was blowing the empty boxes off the line before reaching the scales. How can such oversights be prevented in similar projects?