Buzzoff, I agree with you. It is almost a complete waste of time!
However, there is a published circling approach at SZG which works quite nicely. Means all your SOPs can be practised, but there is a set procedure to do the approach, so it doesn't matter quite so much that you can't see the runway until you get around the corner.
It meets the JAR requirements for practicing the circling approach, and makes a bit more sense than flying a blind circuit.