Sewing thread is different from embroidery thread. It is usually thinner and stronger.
Our sewing process is first single stitching - to join 2 panels together.
Double stitching secure the inner tapes also. Peak stitching prevents the under peak from being bulky, as the peak/brim is usually curved. For easy identification of the cap size, we usually make 6 rows of peak stitching caps. 4 rows of peak stitching for child sized cap. 2 rows of peak stitching for baby sized cap.