Most sites are covered by a long list of regulations, standards and internal policies, but only some of them apply to any given procedure, and figuring out which ones usually depends on the experience of whoever wrote it. That makes it easy to miss a requirement or to cite regulations that do not really apply.
The better approach is to map regulations to the equipment, activities and hazards they cover, then match procedures to them through those same attributes. Once that mapping exists, it becomes clear which regulations each procedure needs to satisfy, and gaps show up as procedures with no coverage for a requirement that clearly applies.