You need to experiment with max_error: 120 from the [verify_heater] section in order to find your balance for your hardware.
The “just right” value depends on many factors, e.g. ambient temperature, thickness of the glass, power of your bed etc.
Note it is a cumulative error, e.g. if your bed is 3 seconds 20°C below target, then this error counter would be at 60.