I’ve had to work with several firms of management consultants working for large corporates. They were used to help deliver big infrastructure projects. I was pretty impressed by all of them. The were seasoned professionals and in this case they were there to help make a project happen. This meant dealing with a lot of the intractable blockers that exist within large organisations. Tensions between different parts of the same company or between the company and its suppliers regarding how much they get for a service.
I was working for a Telco that had won a contract to redesign a huge enterprise network and I was really working with the consultants to deliver it. They never really get their hands dirty with technology, they were never techies, but they understood the issues. What they did was really help the client move forward by applying a bit of oil to its processes. Where there was a contention between the supplier and the client that was raised and not fudged. If two supplers had some conflict, they would be the ones to knock heads together on behalf of the client.
Consultants are used as hired guns. When a company is spending money on projects and expanding, it is a lot easier than if it is in trouble and contracting. In the latter case they are used to do the dirty work and look for ways of downsizing the payroll without losing some of the key players. Consultants tend to be used to do the jobs that a client does want to or cannot get its own people to do. When they job is over they go on to the next project. They get paid a lot, have to travel anywhere at a days notice and have to show high levels of commitment and professionalism. They are usually charged to the company at several thousand $ a day. McKinsey probably are at the top end.
At the other end of the scale there are consultants who are not really consultants at all. They are young graduates at the beginning of the their career who have wandered into some agency that is a body shop. They find their new job is not with the company they thought it was, but instead that they have been sold into slavery in some dysfunctional corner of a large corporation or government department. They are there to be charged out at some day rate to fullfill a consultancy post. Their salary is in no way connected with how much they are charged out at and their contract might have several layers of other contracts above it. A lot of the big accountancy firms have consultancy arms because they can see where a company is losing money.
If you meet consultants when you are in a fairly low down to pecking order in a company, it is usually bad news.