I didn't have a problem with "where" to stipple (ie direction), it was just the mechanics of doing it. The larger pattern requires a larger movement of the quilt which I found difficult to constantly adjust and the larger movement combined with my machine speed was not matched - hence the thread breakage. I did have better luck when I increased my machine speed, but I still had some breaks.
I was also using a lighter weight thread (Aurifil 50 wt). In hindsight I may have better off with a 30 wt. I later discovered a spool of blue variegated 30wt that would have been perfect.
I'll have to do some practicing of larger stippling ... see if I can find a better machine/hand speed combined with a heavier thread that will work.