This may seem wasteful but I change my bobbin every row when doing pantos. I hate getting into the middle of a row and run out of thread. I always check my bobbin when doing freehand work after I finish a certain portion of any quillt. I would rather finish an area and cut, knot and bury the thread rather than have to unsew several inches of finished work to get enough thread to knot and bury.
This is a lesson I learned with a lot of practice and yes the end of a bobbin doesn't sew as nice.
I transfer leftover thread to bobbins for my DHM for quilting small projects so I am not really wasting a lot.
peace