Why are some stars in the zodiac on duty for two consecutive days? How to choose the date?

Twelve satellites (twelve digits) represent twelve days of construction, division, filling, leveling, determination, persistence, breaking, danger, success, closing, opening and closing. For example, in the next year, the child will be built, the ugliness will be removed, and the number will go; Ugly year, build ugliness, divide yin.

Twelve satellites are built twice a month, namely, the first lunar month, the second lunar month, the second lunar month, the third lunar month, and so on. The first month is, so two of the six cloudy days (Jiayin, Bingyin, Wuyin, Gengyin and Nonyin) must meet the sword. February is, so two of the six dates (Yi Mao, Ding Mao, Ji Mao, Xin Mao and Gui Mao) must meet the sword, otherwise it will be wrong. Every solar term (beginning of spring, Qingming, Qingming, Long Summer, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, heavy snow and slight cold), both satellites are very important, so as to ensure that the first day of this month is the same as the monthly branch and "construction".

(It's not easy to understand here)