We tend to do two medium-length stopsets just before the top and bottom of each hour, with a third stopset around :40 past when absolutely necessary. No more than three.
I guess I don't read too much into pros and cons with stopsets, just as long as they are separated enough to not run into each other on heavy commercial load days. There is nothing worse than hearing a station that takes a commercial break, plays one song, then stops down for another break. With our automation system, I make use of sync codes to drop songs so that the stopsets run on time. We may lose one song in a music set, but it's better than having commercial breaks crowded together and playing fewer songs later.