Normally there are lapped side seams on a men’s shirt. However I am not doing it that way because it is way too time consuming and difficult for me. I am cheating here because there are so many other complicated phases on sewing a men’s shirt where shortcuts cannot be taken.
I sew the seams normally with a straight stitch and finish the raw edges with a serger. After that I just topstitch the seams from hip hem to wrist. The seam becomes just as durable as lapped seam would be. Naturally wrong side of the garment won’t be just as neat but the end result is just fine for my needs. Also I am not having bad conscience because my idol Peter Lappin blessed this method on Threads Magazine podcast seventh episode as well (position 0:25 onwards: “– nobody has to know–“)
However it might be a bit tricky to sew the underarm seam as you need to “sew in a pit” which you can see in the video above.