Many people may believe a supercharger is creating boost 100% of the time. As previously mentioned, this is not the case. The blower normally goes on boost when the throttle is opened substantially, or when a load is put on the engine, such as two-up riding, or going up a steep hill. In order to create boost, the supercharger must get air, most street riding is done at slight throttle openings which restricts airflow. Interestingly, even when not producing boost pressure, the spinning rotors improve engine volumetric efficiency to the point where you can maintain high cruising speeds at lesser throttle openings, and in around town driving conditions, the engine will appear much more responsive.
Boost is affected by many factors, including (but not limited too)