By using the same weight, water temperature and steeping duration, all of the teas are treated exactly alike. While teas are naturally grossly over-steeped with near boiling water, (which is counter intuitive to making a great cup of tea), this method of employing extremes brings out the characteristics of the teas to the highest degree, allowing the tea professional to quickly assess both the strengths and weaknesses of the tea.
Generally the buyer will be sampling one kind of tea and therefore judging many different options of the same tea. For example, (s)he will be tasting five or six different Lishan teas or Asian Beauty teas (if in Taiwan). From time to time, a seller will also include a sample that is a different kind of tea to the others.
If you want to learn the ins and outs of cupping, hop on over to Seattle this weekend to check out the tea cupping workshops offered by Suzette Hammond at the Northwest Tea Festival.