I also fill every bobbin that i have when I run out. I is soooooo nice to just reach into the case and find one ready to go. I do need to plan ahead. More than once I have filled all or nearly all of my bobbins and found I did not have an extra spool for the machine. Silly me! Off to JoAnn's, closest store for thread, I would go and use what ever coupon I had at hand so I could continue with my project.