I believe that's the reason for the magnetorquer? There should be very little reason for a satellite to build up angular velocity beyond very small imbalances l

I believe that's the reason for the magnetorquer? There should be very little reason for a satellite to build up angular velocity beyond very small imbalances like from atmospheric drag. The needle of a high quality compass seems to have plenty of torque. It probably used propellant initially, though. Using the propulsion system frivolously could even be detrimental for various reasons. Depending on what it is, it could cause degradation to parts of the satellite like its optics or solar panels. During scheduled thrusts, the satellite could have to orient mechanisms a certain way or close an aperture.