When you are putting a full sleeve into an armhole opening, there are some choices on how to manage that extra fabric in the sleeve cap.  The usual way is to sew a gathering stitch between the notches in the sleeve cap and ease the fullness with gathering.  Another way would be to distribute the fullness evenly into small pleats in the front and back of the sleeve cap.  Alternatively, the fullness could be taken up in one pleat at the shoulder, either in one front-facing pleat, or in a box pleat (the extra fabric divided at the shoulder).