Prasad posts on an approach to HR consulting he dubs "wisdom consulting". As he explains:
The kind of HR consulting that I now look forward to do goes beyond tools/ techniques/ methodologies/ approaches. It is highly customized (to the client context) and highly 'personal' (that would enable me to 'bring more of myself into the work'). In addition to the difference in terms of the degree (of customization /personalization), there is also a difference in terms of the intention (see the note below). This way of consulting mainly uses patterns/broad principles (and not methodologies) so that effective solutions can be developed and implemented in complex and dynamic environments.
This got me thinking, that traditionally consulting (the advice business and not technology services or outsourcing that goes by the name of consulting these days ;-) has been of these two approaches. The wisdom of 'thought leaders' like Drucker or other pathbreakers in their fields has been markedly different from the tools, methodology laden focus of larger consulting firms (for example, BCG's 2x2 product matrix). The focus of course is as Prasad mentions on the leverage that tools provide.
However another difference is the purpose of the consulting assignment itself. Larger consulting firms are driven by the expertise model. They are sought to be hired for a skill (of strategic analysis, financial modelling, business process mapping etc) that are lacking in the client system. The end result is a report and a choice of decisions that the client needs to implement.
However, in the case of a single person 'guru', what the client is hiring is not so much of 'content' expertise as it is 'insight or process' expertise. Their focus is to help the client discover the issues/blind spots that is holding it back. The aim is the develop the client system's internal processes and learning so that the next time there is an issue they can solve it for themselves.
Of course, sometimes larger consulting firms also do the collaborative consulting approach, but they cannot be done by all consultants in the firm. It is usually handled more by internal thought leaders of the firm, like Arun Maira of BCG does in India.