You will learn though - how many you need per size, per density. It's not only the size, but how much thread you lay down for that paricular quilting pattern on that size of quilt. Make sense?
Until you get extra threads for those colors you use alot, you may need to wind them from the same cone. You probably will never duplicate all your threads, only those you use all the time. That's the drawback of the onboard bobbin winders. One idea would be to wind the bobbins in advance, if you know what you're going to use on the next quilt and have a good idea of how many you'll use.
Otherwise, sorry...I have no great words of wisdom - except perhaps to get a second bobbin winder :(
Yes...stuff happens :)
Debbie in Austin