Research cited in a recent book I read, Business Consulting by Richard Toppin and Fiona Czerniawaska, found that for many management ideas, early adopters do best, laggers do worst. That conclusion may hold true for law departments.
By the time a slow starter adopts a once-popular management idea, those departments that got their first and have charged on may be benefiting from another generation of breakthrough concepts. I suspect one might have found this with bill auditing by external services demonstrated this shift. The first departments gained some data and leverage, but the late adopters ran into a resistant group of law firms, overly-aggressive auditors, fewer egregious practices, and a surfeit of poorly trained auditors.