I have been involved in a consulting team where our leader already thought the deal was going to bring the synergies we calculated. However, as I am sure most know synergies are often miscalculated and specifically when you work in consulting you are dependent on the information given by the target company and the buyer. These can often be misleading, false or just not enough information. In our case, we did not review the work done at due diligence and it brought issues at the integration level.