Admission in US universities

The rainbow scientist has an excellent two-part series on how to get admission in US universities for science and engineering. Many of the points there are very valid and easy to follow for a student aspiring to go abroad. However, the author mentions "you can work hard for an exam, get maximum marks in your entrance exams (NET, GATE etc) and can be happy that you will be admitted at the best institute according to your score, but most of the American Institutes believes that single day performance can not judge you and your ability to pursue a tough and competitive professional program."  But this is not strictly true even in India. The exams are used only as a filter for an interview. In the interview, especially in IISc, we do try to judge the student's ability to think, do research etc. The author also mentions, "American Ph. D. program is in general 5+ years, with committee exams at 1 1/2 years, 3 years, 5 years and final defense." However, one can finish Ph.D faster depending on the work. For example, I finished my doctorate in 25 months in USA.