Nice post. Actually, the required band score varies over different departments under the same university. Naturally those arts programs requires higher Ielts scores than sciences and engineerings, and business as well. I heard of that the highest overall score required in the world is 8.5, which is for the Graduate School of Journalism at Columbia University. That school must be crazy. Applicants from non-English speaking countries almost cannot compete. Personally, I think 6.5 is the minimum for schiences and engineerings, 7.0 for business and economics, 7.5 for arts programs, like history, linguistics, philosophy, communications, etc.