The vast majority of comments here are from people with first hand experience of the level of incompetence from large I find consultancies. I have personally witnessed a major Indian IT consultancy cause problems with a file server migration. They had no idea that you needed to propagate permissions from the base folder. This took out production for 8 hours.

In the end, an on-site employee took over and fixed the issue in 5 minutes. It was pathetic to watch.

One day there will be a reckoning for these large consultancies. On that day, virtually no onsite IT employee will be unhappy.