Why doesn't the master have to look at the solar time?

Looking at the sun time can't tell the time completely accurately. Apparent solar time refers to the time when the sun reaches the highest position of the observation point in a day. Because the earth's orbit is elliptical, the earth is close to or far from the sun at different times. Therefore, depending on the solar time can't express the time completely and accurately. Therefore, the master did not use the sun time because the sun time could not express the time completely and accurately.