Follow the manufacturer's finishing sequence, which commonly includes a short water rinse after the grinding sound has finished and the motor has stopped. That rinse helps move remaining particles beyond the chamber.
What the observation tells you
Turning both tap and motor off together can leave waste in the outlet path. Conversely, prolonged running will not repair a restricted drain and can cause a backed-up sink to overflow. There is no universal rinse duration for every installation.
A useful next step
Use the duration in your model's instructions. If normal rinsing produces standing water, stop adding waste and have the drainage problem assessed.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.