Train movements, not muscles by isolating them, UNLESS it is for rehab/corrective/restoration purposes. Most bodybuilding techniques are minimally used here as we are generally trying to increase GPP, relative strength, work capacity, and thus are trying to increase parameters of physical performance and improve athletic potential. Bodybuilders tend to isolate body parts by using “piece meal” split routines that are extremely inefficient, lead to muscle imbalances, loss of range of motion and actually create more work for you in the long run, and more days and hours in the gym. Loss of ROM can be seen very simply by observing the average bodybuilder perform a Standing Military Press, Overhead Squat, or Pull up. The lack of ability to complete a full ROM on these exercises clearly demonstrates how certain Bodybuilding techniques, as well as training in isolation can significantly impair optimal biomechanics, which can and will ultimately lead to dysfunction and injury.
However, if you go to your typical commercial gym, you will see many people working out this way. WHY?