Lie back on the bench, shifting the dumbbells to your chest with your elbows at a 45 degree angle relative to your torso.
There are a few reasons for this, but the main reason most people should do full-body workouts over split workouts is time.
Depending on your goals and experience level, it's the type of routine that you can use once in a week for a three-day split or even double-up for a six-day ... part of a push/pull/legs training ...