When done properly, super circuit training can be very effective. For example, three minutes on the treadmill, then one minute leg press, three minutes stairclimber, one minute lunges, three minutes cycle, one minute lat pull-down, three minutes rower, one minutes bench press, etc.
Advantages to this type of format are that it helps eliminate boredom, can work equally well for class-type settings as well as one-on-one, and allows a large amount of total work in a short period of time.