Do patients have to stop taking accutane (Once treatment period is finished) gradually or suddenly?

I am on 10 mg Accutane for two months now, and the doctor has just prescribed me 20 mg for the next two months. He said that is all i need to get my face clear up and i do not have to come back to him because by then my treatment will end. My friend stopped the treatment gradually, so i want to know does this increase the possibility of acne coming back again? Also, i still have under skin pimples, so i am in doubt that such a low does will get them to pop out or fade in 2 months.