I've talked about biomechanics and movements (bad versus good )
We all know you cannot change the shape of a muscle, the pec does attach at certain areas, but all those fibers insert to one position under the arm.
conceivably one could work the "upper, middle and lower portion, would that be enough to change the shape?
i don't think so.
or maybe you need to use a lighter weight because of the awkward angle, this is most likely.
size is stimulated by load and work, not my changing angles.