I wouldn't hold any special reverence for McKinsey.

In general with any of the management consultants, you're going to get people with very little actual experience telling you how to run your company.

Whilst some of the stuff, usually more accountancy / factual based, doesn't require experience, and thus may be delivered to a high standard, you're also going to got a bunch of hot takes that don't make sense in reality.

Outsourcing, the Spotify model, and not really agile Agile are all sold by the top tier consultants, even though you basically can't name successful examples.