So I've done some more fancy fenangling (by which I mean basic math), and come to some conclusions. I am on ball 7, and finishing the third repeat of chart B in Frost Flowers. Doing the pattern as written, the end of this chart would have had me at 30.6% of finished. This would be fine were it an even 1/3 of the way, but that 3% got me nervous. One third of 22 balls? Seven and one third. That's finishing with room to spare. 30% of 22 balls? Six and two thirds. So as you can see, I'd need to get at least 7 balls out of 30% to be comfy here. Ergo, I could either order more yarn with no hope of getting the same dyelot (seriously, NO hope), or I could eliminate a repeat of the chart. I have opted for the second, which will give me a 5-foot shawl instead of a 5-foot-6-inch shawl, but will leave me with my sanity intact, and is still more shawl than I'm likely to need in Texas.
This, of course, needs a new graphic:
Glorious, is it not? So now, instead of being almost 30% of the way finished, I'm almost 35%! Yay Frost Flowers! Yay me!