Most uncertain Mahadasa, Rahu mahadasa. In my experience I have seen person moving around aimlessly. They donot know anything about their future andvery much worried about it. During this period a person can suddenly get a leap in life without much effort.
He himself will be surprise when he look back at his life. It is because of Rahu’s nature. When Rahu wants to give, then it will give by any means, be it by good or bad mean. By hook or crook. Rahu creats an illusion in the mind of the person who is going thru it's period, an affinity for materistic world.
To achieve this Rahu inspire the person to go for shortcut way or unethical way. Its main aim is the achievement. In over night Rahu has got the power to make a poor person rich and a rich person poor. Thats the reason, if one wants to see the luck in gambling, then rahu is to be studied in his horoscope apart from 5,6 and 11th house.
During Rahu dasa it is seen that medical diagnosis doesn't yield good result. Doctor remain confused about his patients as diagnosis doesn't detect the real cause of the disease. Rahu dasa will give its result according to the placement of Rahu with other planets. So the effect will differ from person to person. But as discussed above in general, the effect remains more or less the same if seen the general effect of Rahu mahadasa.