i don't know about you, but i have to pay very close attention when i stitch to make sure all my seam allowances are consistent. if there's so much as a thread or two's difference from patch to patch, i can end up in a real pickle.
i also need to break my very bad habit of using different rulers to cut different sets of pieces for the same project. even when they are all the same brand, there can be significant differences in the measurements you get. all quarter-inches are not created equal. :?