Should PhD be 3 years?

Before I started my studies, I used to think that PhD shouldn’t be three years. It is not worth it. I always asked myself “what do PhD students do during 3 years? It is just a research and a dissertation that can be done in 2 years at maximum”. After I started my PhD, I realized that even 3 years may not be enough. In the first year you need to get a comprehensive literature review done and put a good annual report to bed, which in its turn includes a very detailed proposal, research plan and background study. You might feel that you are familiar with your research area but the literature to study is enormous. You finish one article and think that it was the last one. But when you reach to the references in the end of the article you find some other materials in the reference list. It comes sometimes that you feel that there is no end for this story. Once you have achieved a clear idea of the past studies and their results, you will be able to plan for the future.
One of the main differences between research degree in Iran and abroad is this review stage. Because of the several factors including lack of literature, inefficient access to material and researchers’ attitude among others, review of the literature is not appreciated properly. I’ve heard of the PhD students who finished their research and then started searching in some databases to just get some references for the end of their dissertation.