I sew more in spurts so don't go long time with no bobbin thread. Time for me can be measured in inches or feet, never minutes or yards. I can't imagine chain piecing 15 minutes with no bobbin thread. I actually can't imagine chain piecing 15 minutes period. The quilts I make don't have a lot of chain piecing. When I do it is for just a few pieces and then those are assembled into a block and I repeat the process. I can't keep the orientation of pieces correct if I get too far ahead of myself plus I like variety. I cut a little, piece a little, press, put on my design wall, question my placement and color choice, rearrange, assemble in block, repeat...