Supersets (doing two exercises directly after each other with no rest between the two exercises) are a good way to save time in the gym. Besides saving you time, this study has shown that using reciprocal supersets (i.e. training antagonistic muscle between in the superset) increases your body’s energy expenditure by over 30% (measured as post-exercise oxygen consumption) compared to a traditional exercise regimen without supersets.
The problem with the study is that post-exercise energy expenditure only was measured for the 60 minutes after the workout, so we don’t really know if the body balances out this increased energy expenditure long term.
But even if this conclusion is uncertain, saving time on your workouts is definitely a plus! We would recommend you, however, to avoid supersets on your heavier compound exercises as the fatigue from limited rest would negatively impact your intensity (i.e. load) in the exercises.
Kelleher AR. The metabolic costs of reciprocal supersets vs. traditional resistance exercise in young recreationally active adults. J Strength Cond Res. 2010 Apr;24(4):1043-51.