Short answer: if your doing something that requires timing resolution below your vector size then this object is inadequate. For instance if you need to change the q exactly every 801 samples use a different object. Otherwise don't worry about it.
This only applies when you connect a signal to the inputs that control frequency and slope. If you would connect a line~ that ramps from 600 to 800 (hz), instead of a continuous change, the frequency would move in discrete steps, one step sampled every signal vector size. In SuperCollider this is called control rate, as opposed to audio rate.