When piecing anything with white in it, white thread it is. For any other color fabrics, I use whatever shade I have handy....usually trying to use up the older, not so fashionable colors. Bobbins are the same.....I will fill 5-6 at a time for FMQ and the leftovers get used first in the next project. I know that my methods aren't to standard, but I refuse to waste thread and this is a good way to use it up and empty bobbins.