72 a year, wait a few days.

Not much. The 72-hour cycle is compiled according to the geography, climate and some natural scenes of the Yellow River Basin, with 5 days as 1 hour, 365 days as 72 hours in a year (average year), 1 day is not much, and 1 day is not much. After 72, after 3, there is a section (qi), corresponding to 24 solar terms; Six qi is temporary, corresponding to spring, summer, autumn and winter; Four o'clock is one year old, corresponding to one year. The time series changes of 72 climaxes reflect the general situation of phenology and climate change in a year.