I got about 6" into the stole I was planning for the Guild challenge, weighed the yarn to determine how much I had used, and did some calculations to see how long I could make the stole.
Unfortunately, that length turned out to be about 3 feet. Not long enough for anything but a table runner, really.
Mutter, mutter, frog, frog, frog.
Now I had the info, though, on about how many square inches total of knitting I could produce with the yarn I had, so I played with dimensions to see what some of the possibilities were for a shawl or scarf. After considering a longer, narrower rectangle, and a square, I settled on a triangle, which allows a top edge long enough to wrap around for a scarf. Nice simple shaping, with the pattern stitches in bands, and an edging to knit separately and sew on. Knit from the neck down, it will be easy to stop earlier or extend if my calculations were off. I will simply have to try the full-sized shawl recreation another time.
However, this is the third project in a row where I've needed to frog and recalculate. It's getting to be a habit. Even if the next project goes smoothly, I will likely spend the whole time I'm knitting expecting it to go wonky somehow.