It really depends on the object you are trying to scan, the lighting on the object, the speed at which you are turning the object, and which application you are using with your Structure Sensor.
Please make sure that the object on the turntable has enough artificial lighting to reduce the number of shadows seen.
Also, please try to scan each surface of the object only once, as scanning multiple times will impede on good results. A full 360° turn is unnecessary.
Here are a couple of links that you could use for tips on how to improve your scans. Though they are for specific applications, the tips can be generalized to the Structure Sensor.