Look at the cat D and higher minimums for circling approaches. The visibility exceeds the visibility required for a visual approach due to the turn radius required at higher speeds.
If your airline opspecs or the manufacturer classify your A/C type as cat D (CRJ200s) there is no sense in training the maneuver since cat D minimums will push the approach into the visual approach category.
I worked at an airline that, for a short time, sold CRJ200 type ratings to people and then hired the ones they felt were competent. The training was done outside of the airline's training program and so they trained the circling maneuver. These pilots were issued unrestricted type ratings. At the same time pilots going through the same training inside the airline program were not trained on the maneuver and were issued restricted types.