I had 5 cases on my final round with BCG. The first 4 cases when very smooth, completely in-line with how I had prepared, the 5th case was a disaster though. The case was about a competitor moving into a different country, all of the numbers indicated it was the wrong move for them so my recommendation was to ignore them. The Partner doing the case told me that there must be a reason for them to move so I should always follow them at least with a small launch to test the waters. It all went south from there. Didn't get an offer.