Minecraft wiki entry for Pulse, associated text: In Java Edition, a piston or sticky piston usually takes 1.5 ticks to extend. If the activation pulse ends before this (because it's only 0.5 ticks or 1 tick long), the piston or sticky piston will "abort" – it will place the pushed blocks at their pushed position and return to its retracted state instantly. This can cause sticky pistons to "drop" their block – they push a block and then return to their retracted state without pulling it back.
A redstone comparator will not always activate when given a pulse of 1 ticks or less.
A redstone lamp can only be deactivated by an off-pulse of minimum 2 ticks.
A redstone repeater will increase the length of pulses which are shorter than its delay to match its delay (for example, a 4-tick repeater will change any pulse shorter than 4 ticks into a 4-tick pulse).
In Java Edition, a redstone torch cannot be activated by pulses shorter than 1.5 ticks.