By going past the end, you can serge over the excess stitches and this will secure them in place.

Continue to serge down edges and go past the edge each time. Turn the fabric each time you start on a new edge.

Another option is to serge down to the corner, stop your machine, and then pivot to continue serging over the next edge. [10] X Expert Source Alessio IadiciccoApparel Manufacturing Specialist Expert Interview. 20 May 2021. This may be a good option for thicker fabrics that are hard to straighten out. [11] X Research source

You may want to just lift the presser foot for the sharpest portion of the curve and then lower the foot back down when you get past this part. Watch your fingers when you have the presser foot up! Keep them well away from the needle.