"How much ya bench, bro?"
Unfortunately, this question has become so commonplace that a casual observer would quickly come to the incorrect conclusion that the bench press must be the primary metric of strength. This has produced a great deal of popularity with the bench press exercise, among other reasons. The mentality of skipping leg day to do chest day again has become so pervasive that it has become an inside joke within the lifting community. Not nearly as bad, but still unfortunate, are those trainees that will bench without pressing in some regimented capacity.
The press is an exercise that is highly effective at building muscle mass and which facilitates a safe balance of muscle in the shoulder. Similarly, the bench press is highly effective at building muscle, but favors posterior rotator cuff muscles over the anterior one potentially resulting in a muscle imbalance and, by extension, injury. The bench press, while useful, must not be favored over the press, and the press must not be ignored.
First, these exercises must be, at least crudely, defined to facilitate this discussion. In the press, the trainee is standing. The press starts with the bar in front of the neck, held by the hands with the elbows generally below the bar. The trainee's face is moved out of the way as the bar is pushed upwards until it is over the trainee's head with the elbows locked in full extension and the bar directly over the shoulders.
In the bench press, the trainee lies down on a horizontal bench with the chest facing the ceiling. The bar is taken in the trainee's hands from supports and positioned directly over the shoulders with fully extended elbows. The bar is then lowered to the chest until it touches the chest. Next, the bar is pushed away from the chest until it is directly over the shoulders with fully extended elbows.
Both of these exercises are essential for building strength. Each build strength fundamentally the same way, but both are used for subtly different reasons. Both the press and the bench press use a long range of motion and can be used for heavy weight. The bench press, however, can be used for far heavier weights, allowing the training of the posterior shoulder muscles and the pecs far more than in the press.
The press, conversely, trains the muscles surrounding the scapula far better. The scapula is a unique bone which rotates as the bar is moved from the start position to the overhead position. If the arms are to apply force to the bar, they must not fall out of the shoulder sockets. The rotator cuff (the muscles attached to the scapula) is key in stabilizing the humerus in the shoulder socket. In the bench press, this is still true, but the subscapularis (a rotator cuff muscle on the side of the scapula that is closer to the chest) is not stressed in nearly the same proportion as the other muscles of the rotator cuff. Because of this, benching without pressing can result in a muscle imbalance in the shoulder joint which can cause injury. Anyone with a serious shoulder injury will likely tell you one thing: shoulder surgery is no stroll in the park. It is crucial that anyone that trains the bench press also train the press, or at least an exercise that stabilizes the shoulder in some capacity, in order to prevent injury.
Besides safety, the press is a movement that produces musculature that is highly effective outside the gym. In the press, the bar is held by the hands which are held by the arms which are held by the shoulders which are held by the torso which is held by the legs which are held by the feet which are held up by the floor. Because this kinetic chain is from the bar to the floor, the whole body is involved in ensuring the bar reaches the overhead position. This is also true of most movements in life. In fighting, the force from a punch starts at the ground and moves up the kinetic chain to the fist. The same is true of picking up groceries and pushing a heavy object to slide it across the floor. The force in the bench press, however, starts at the bench and moves through the kinetic chain from the back to the shoulders to the arms to the hands. This does not frequently occur in life and therefore will not be as effective at building strength which utilizes a foot to hand kinetic chain which is used frequently for life and sport.
The bench press is a useful exercise, but if a trainee has to eliminate either the press or bench press from the program, the clear choice is the bench press. The stability in the shoulder along with the strength built from using the entire kinetic chain in the press is unmatched. If a trainee's bench press is at 315lb and their press has not reached 185lb or a female trainee has a bench press of 135lb and cannot press 65lb, this is a wake-up call.