You are describing my field - Systems Engineering.

We track EVERY requirement to ensure it is met. Maybe it's a safety issue; maybe it's landscaping approvals (I work in Rail). Regardless, it's bigger $ if not caught up front, and if you start grading requirements on perceived risk, you start the slippery slope to not caring. Example: mark all landscaping requirements as "Not Critical". Then scheduled clearing of the right-of-way is missed. Then pedestrians are at risk with blocked line-of-sight, and trees might drop across the rail.