Tapered insulation can form part of a designed drainage solution, but it must be coordinated with drains, edges, equipment, and the complete roof assembly. It is not simply a thicker version of ordinary insulation.
What to do next
Ask for the layout and explanation of intended water paths. Review how the added assembly height affects curbs and transitions. Keep the drainage design coordinated with other project documents so field decisions do not undermine the intended result.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.