And, how about these:
- The final block is not the same size as the other blocks?
- The final block's edges are not straight?
- The final block is not square?
- You had to cheat on the seam allowance and it still didn't come out square?
These problems happen when you use the "Sew & Flip" method, or use templates, or just measure and sew.
These problems are not anyone's fault - they are due to the "physics of fabric".