It should be a part of training.
If your elbows are dropping below the plane of your back due to any number of anatomical issues,you at that point are stressing your shoulders and engaging shoulder muscles and back. At that point most roll their shoulders forward to push the weight yo and arent oress/squeezing their chest to get the weight up.

A simple way to check this is to bench flat on the floor. See where the bar is when your elbows bit the floor. Any fsrther oast that point starts to do what i was saying above.