In a personal horoscope, the sign on your ascendant (rising sign) changes every 2 hours and the degree changes every 4 minutes based on what time your were born..
The location of birth aids to find the exact longitude and latitude that is part of calculating a correct birth chart.
No chart repeats itself for 26,000 years.
Your personal chart calculated for the time, date and location of your birth is a key to this current lifetime.