Rome was not built in a day. The same can be said of the value that an enterprise receives from its legal advisers.
The business of law is built on long-standing relationships. Company executives must feel comfortable that their lawyers understand the nuances of their business, its strategy, and their goals over the short, medium and long terms. Of course, one need not mention that trust and secrecy are integral, even foundational, to the relationship.
The intersection of the law with the realities of business is a complex calculus that gets easier to solve over time. There is intrinsic value to the enterprise in avoiding repetitive reeducation of counsel. Did you absorb any version of calculus in a semester, much less a day?