Take a big construction project. In the like of the Berlin airport. What do you think is more profitable for the consulting companies :
a) A well thought project, done in budget and in time. Where the consulting company gets the whole contract + all the bonuses associated with it.
b) A poorly managed project, that gets refinanced multiple times and that ends up being pushed back decades.
It's actually B. Consulting companies love long projects, because this allows them to place consultant for extended periods of time. And any consultant working for a client is a profitable consultant event without bonuses. Consulting companies hate projects that end up shorter than expected, because any bonus they might get from that project ends up being spent on consultant that are waiting for their next assignment.
The main KPI of any consulting company is "the %age of time you consultant are spending 'on assignment' vs 'on the bench'". And long projects where consultant are busy for years are the best way to bring that KPI to 100%, even when the underlying project is a complete mess. The only thing they get from shorter and better managed projects is a better image, which is easier and less expensive to get using marketing technique and PR.