Due to the nature of the sentence construction, I can't understand even what you're trying to ask.
By accessory belt, do you mean the serpentine belt? Serpentine belt plus an additional V belt driving A/C compressor? I have no idea.
All belts rotate at engine speed - whether it's at idle or at 10,000 RPM. The pulleys driven by the belt can rotate at higher or lower speeds than the engine speed depending on their diameter relative the pulley driving the belt.
