Oh yes, we all have our moments! I have a D9P set on point with sashing. I got all the blocks together, all the triangles except for the corners. Laid it all out (late at night) and thought I'd be less confused if I cut the extra points off the sides, top and bottom. I didn't realize until the next day that I cut off a row too soon! Now I have to make more blocks and rip out the last blocks along one side and bottom, shift all around, add new blocks and triangles. I was so discouraged that I put it aside. I'm hoping to get back to it one day soon though. It is a pretty quilt.
Lesson learned: do not cut when tired!