Originally Posted by CanoePam

a serger sews at a much faster speed than a regular sewing machine. A domestic serger can sew pretty much as fast as an industrial straight stitch, 1000 SPM or more. For the Olson mask, you just serge the edges, no folding under and top stitching. For a pleated mask, you can serge the pleated side faster than sewing because sergers handle wider variations in fabric height than sewing machines. They don’t do casings well, and it is easier to apply a binding with a sewing machine though so not all steps can be done on a serger.