Short Answer
Yes. Insulation and ventilation are related but serve different functions. Insulation reduces heat transfer. Ventilation manages airflow and moisture within appropriate attic spaces. Air sealing is another separate consideration.
Detailed Explanation
Insulation, ventilation, and air sealing are three separate but interacting systems that all affect roof performance. Insulation slows heat transfer between the living space and the attic — keeping heat in during winter and out during summer. Ventilation manages the airflow through the attic to remove moisture and excess heat. Air sealing closes gaps and cracks that allow warm, moist air to leak from the living space into the attic. If insulation is inadequate, excessive heat reaches the attic, warming the roof deck and contributing to ice dams and shingle aging. If insulation blocks soffit vents, it prevents intake ventilation from working. If air leakage isn't sealed, warm moist air enters the attic regardless of insulation levels. All three need to work together for optimal roof performance.
Why It Matters
Insulation, ventilation, and air sealing are interconnected. Addressing only one without the others can create or worsen problems.