Garment seams?

Commercially made t-shirts finish their side seams with an overlocker. Would the zig-zag in lesson four be an appropriate way to finish these seams? Or is the fabric for t-shirts not likely to fray (and so just the straight stitch is enough without anything further)?

If you're working with a woven fabric, a zigzag stitch is fantastic for finishing the seams. It really does cut down on fraying!

Knit fabrics (or t-shirt fabric like jersey cotton) don't need any additional finishing - but I do recommend trimming the seams down a little. Sometimes the excess fabric can curl into the seam, making the seam look bumpy. That's typically why knit fabrics are sewn with an serger - it makes the seams lay nice and flat. :)