A good astrologer can accurately predict up to 70 to 80 percent, especially when time of birth is accurate. This is just my observations over the years. Sometime success rate touches to 90 percent. However, many astrologers (no matters how experienced and intuitive they are) do fail miserably. Astrological predictions fail mainly because of misinformation or disinformation about date and time of birth. The second reason is the human error (i.e. astrologer’s fault) that could arise due to incomplete knowledge of astrology, limited practice, fallacious analysis, poor judgment and/or personal biases.