Dear Srinivasan, the least period that you can complete any course is the minimum duration of that course. For example, if MBA is for 2 years, the minimum period of time that you are supposed to srudy that course is 2 years. While the maximum period can be extended upto 5 years, he minimum period cannot be compromised with because the curriculum of that course is designed for that period. PG Diploma is usually 1 year and again as its curriculum  is designed for that period, the minimum duration cannot be compromised or further reduced.