Fast-forward 10 years, and now you're a pretty big company. You want to start manufacturing your product yourself instead of sending that work out to someone else. Do you know anything about managing a manufacturing operation? Say you want to acquire a company. Do you know anything about integrating it?
I think it provides some value, but I am not a huge fan. In my experience, the devil is in the details and the failures come during the implementation, and the management consultancies in the Marvin Bower tradition explicitly side-step implementation.
That is also a practical reason why consulting firms hire from Harvard and care about SAT scores. Getting a 1600 SAT doesn't mean you're a good manager. It's probably a good indication you're good applying abstractions to concrete situations.
Most big management consulting firms these days also do both management consulting and system integration. The margin on management consulting work is sick, but the projects aren't that big (a few million dollars over a couple months). The margin on implementation projects is much lower, but the projects themselves can be enormous (think hundreds of millions over several years). So you're fucking your implementation guys if you deliver an unimplementable plan. And in a partnership model, if the implementation project fails, the partner who did the management consulting piece of the work still takes a hit.