My comment here might give some intuition for it: https://news.ycombinator.com/item?id=44576004 https://news.ycombinator.com/item?id=44576004 . You do need to m

My comment here might give some intuition for it: https://news.ycombinator.com/item?id=44576004 https://news.ycombinator.com/item?id=44576004 . You do need to measure for some time, because the measurement of the clocks with respect to each other is noisy, but you don't need to wait for there to be a whole 'tick' of extra time between them.