In many cases, I will analyze the instructions very carefully before buying fabric.
One specific instance stated I needed 1.25 yards of a certain color. The picture only showed a minimal amount of it. I read the cutting instructions. "Cut four 2" strips." I kept reading, wondering if there was more to cut from this color for a different part of the project. It turns out it was just a printing error. Only needed 1/4 yard, not 1 and 1/4. So I only bought 1/4 yard, and made the penciled in correction on my pattern.