Minecraft wiki entry for Pulse, associated text: Once it has begun its output pulse, the pulse divider goes through a reset period of (2 × pulse count) ticks (the same length as the output pulse). Any new input pulses during the reset period will not be counted, but will only extend the reset period. Because of this reset period, this pulse divider is best when the typical interval between input pulses is greater than the reset period, or you can run a line back from the output to suppress inputs while it is resetting.