Once a law department has converged its law firms and designated a handful of them as preferred counsel, entitled to certain kinds of work and volume over a period of time in return for beneficial fee arrangements and other investments, one can imagine these arrangements encrusting, like stalagmites, unwanted complacency.
Inside the company, lawyers could have a tendency to be easier on the preferred counsel, perhaps due to familiarity or the leverage the firms have. Inside counsel might not demand innovation and variation on how matters are handled, having become comfortable with the routine. Unwilling to rock the boat, they might acquiesce to sub-par performance and loosening responsiveness.
On the law firm side, with less apparent need to market, they might lose the spur of hunger. Acquiring institutional knowledge and hooks, embedding themselves in a comfortable relationship, firms can exhale and perhaps let high standards of quality or productivity slip.
Both sides having sated the hunger of buyer and seller can ooze into uninspired complacency