If a person knows before hand that some thing is going to happen in future. He mentally and physically prepares himself by taking precautionary measures to face the situation boldly and try to over come the situation to get success easily instead of getting defeated. If same calamity happens suddenly when he is not ready to face it. That is why we must know at least some indication regarding what is going to happen in future, in general, and what is going to happen in near future in particular.
If a person knows his future before hand, he will not face any kind of disappointment. As a preventive measure, if propitiation is done for bad and ill placed planets the intensity of bad result will be reduced and the person may be saved from accidents and diseases.
A weak person may become strong by doing exercise and by taking proper medicines and health tonics. In the same manner, by doing propitiation, the planetary influence will be modified, the intensity of bad effects will be pacified and good results will follow i.e. longevity will be increased, accidents can be avoided. There is no doubt about it.
It's like using google map to find the location/destination in the new city or area or country.
Astrology is not only a guide in one aspect, but it is a guide for other sciences also. Astrology will be a guide in weather forecasting, physiology, psychology, geography, architecture, medical science etc.