How to answer the question properly?

I like to look into this topic called how to answer the question properly, specially in the onsite interview.

I should be able to answer the question directly, give out the answer, and then do not talk more. It is important for me to help the interviewer to evaluate a lot of things in the onsite interview. The interviewer prepares a lot of questions to ask me, if I use more time than needed, then the interviewer will not have enough time to complete the assessment.

I was complained back in 2010 June when I joined the current company. But I still have the same issue.