25% of individual seconds, but the average over an hour should be rock solid to several decimal places.
I think the more interesting fluctuations are those which change on an hourly ("checking the clock", spikes when people hear a chime or get notifications on the hour), daily ("eating lunch" spikes when UTC+8 hits lunchtime in eastern China and craters when it's noon in the middle of the Pacific), or other periodic basis.
I think the more interesting fluctuations are those which change on an hourly ("checking the clock", spikes when people hear a chime or get notifications on the hour), daily ("eating lunch" spikes when UTC+8 hits lunchtime in eastern China and craters when it's noon in the middle of the Pacific), or other periodic basis.