I love my serger, I bought it back in 1990 and have sure gotten my money's worth. I serge all seams if I make anything except piecing quilts. But I do serge the edges of fabric before washing. Keeps it from fraying.
I will be picking up another one tonight from a friend. She only wants 25.00 for it. She upgraded. My original one is a Singer Quantum Lock 5 thread. The one I'm getting tonight is a Janome 134d, 4 thread.