Supersets were developed to help get more training done in less time. There is way more to supersets than that. For example if you super set bench press with Rowing. Some of the same muscles are used in both movements such as shoulders , upper back and lats. By combining them in a superset ( 2 sets done with no rest between the 2, rest only after completing the 2 , then repeat) , you are working specific fibers harder or may require more fibers to be activated thereby increasing the stimulus for muscle growth.
Some very good examples of supersets are:
1) bench press and rowing(any form is fine…ie: t bar, cable, machine etc. remember to use a medium to wide grip and pull to the upper chest keeping elbows out.)
2) chin ups/pullups/lat pulldown with Overhead presses
3) Dips supersetted with upright row using trap bar. ( can use 2 dumbells held the same way, parallel to the body if a trap bar is not available) ( this is an exercise I developed….. never seen or heard of anyone ever doing it before) It really helps to activate maximum fibers in the shoulders and upper back…)
4) Back extensions with angled sit ups/ hanging leg raises
You will notice the exercise combinations I described are the exact opposites of each other……