everyone knows the great advantages that scapular retraction provides in bench press (discussed for example there).
The scapulohumeral rhythm is generally accepted to be 2:1, which represents 2° of humeral elevation for every degree of scapular upward rotation.
To visualize it, let's consider the following picture:
To let the shoulder-blades follow its natural movement and prevent shoulders injury, there are some sources (1,2) that suggest not to retract the shoulder-blades in shoulders exercises like lateral raises and overhead press.
Since in bench press there is a certain amount of shoulder flexion (you start with the barbell at the sternum or nipple height with the shoulders partially flexed, and you end with the barbell above your shoulders hence with the shoulders more flexed), this means the shoulder-blade has to rotate a bit upwards to follow its natural pattern. This movement should be performed by the serratus anterior and the upper and lower traps. However, in bench press the shoulder-blades should be kept fixed, stable, retracted and depressed. Isn't this a contradiction? The shoulder-blades are said to be kept packed. But their natural movement is a slight upwards rotation. Should I perform it while bench pressing?