A fundamental problem with any kind of organized selection of counsel – anything more disciplined than a senior lawyer picking up the phone and calling a known partner at a familiar firm – is that the process takes time. Say what you will, a competitive bid process adds time and distraction. Sugar coat the benefits of strategic sourcing howsoever, more people and their tools and steps complicate the simple telephone call. Praise fixed fees all you want, they are no instantaneous fix.
If given the choice, what lawyer in a law department willingly signs up for delay, questions, data collection, and coordination with others when they can just proceed as always? All processes take time, yet only with processes can you stem the tide of costs.