... Well, the "gang of 4" (of which Deloitte is one) - from my experience - doesn't have the good expertise in-house either - when needed, they subcontract or outsource to the specialists... (And I am speaking as someone who has worked alongside them, and also subcontracted with them - I generally warn my clients about the A/B/Z-team game and that they would be better off by contracting with smaller agencies or individuals who actually would "embed" better in their project/team/initiatives)

And apparently so much so that they feel they can even use AI-created reports/materials...