Is it a UFO if you didn't even finish making the blocks?
My recent UFO is because of the pattern. There were 14 fabrics and 16 pages of instructions. Each page had multiple blocks to make. I sourced all the fabrics and proceeded to number each one to keep them straight. I even purchased dies to make the cutting easier for some blocks.
Even with careful cutting and piecing, some blocks are still not coming out to size. They will have to re-done. At this point in life, I'm not interested in frustrations.
Another set of instructions (same vendor) were lacking with instructions on the finishing technique. I managed to finish it my own way.
There is certainly a way to write and "not to write" patterns. I'm putting the blame on the instructions.