Sewing is so different now. When I was young I made all my own clothes and you purchased thread to match the garment. After that garment was finished, you probably would not need the bobbin with that particular color on it anymore. I remember only having a couple bobbins, but why store a bobbin with thread on it that will probably not be used again. Being a war baby, I was brought up being quite frugal. Now, with quilting, I only use a few colors and have bobbins with each of the colors on them.