1) Doing a bit of math my help the beginner to understand the limitations and trade space available to when flying the maneuver. The FAA has taken a crack at this for no wind with for us when setting up the A-E category minimums. These have recently been revised as they were a bit optimistic about what could be accomplished safely.
2) As a GA pilot who fly's a bit of IFR into small airport, I have performed as many real (IFR and not training) circle to land as I have real ILS approaches.