Benchmark data tells us that the tipping point for having a full-time administrator is around 10 to 15 lawyers. In that range, more departments have an administrator than do not have one (See my posts of April 8, 2005 on replacing an administrator with rotating lawyers; Aug. 1, 2006 on various titles for the position; and Oct. 1, 2006 on this metric.).
To my surprise then, I heard of a law and compliance department with more than 400 people that has no administrator. Instead, this very large group relies on a finance person assigned to the law department, and an HR person also assigned (See my posts of Nov. 8, 2005 on the contributions of HR reps; and Dec. 2, 2007 about the Time Warner Cable example.). I do not know about the status of IT support. The general counsel explained that there is no chief operating officer or administrator for the department. The same held true for the law department of Oracle which has almost 100 lawyers.
It is hard for me to understand why such large groups do not feel it worthwhile to have a person in charge of infrastructure and legal operations (See my post of Feb. 7, 2008 on infrastructure.).