Administrative costs bear little, if any, correlation to size of districts over 10,000 students, according to Utah fiscal data from 1998-2001.
A post from 2014 demonstrated the same thing. Similar findings are observed with more recent data (Fiscal Years 2023):
a June 2022 Performance Audit of Public Education Administrative Costs in Utah noted that “some of the lowest administrative costs per student are among midsize and large districts (i.e., those with student counts of 10,000 to 20,000 students)”
Another key finding was that “Administrative cost spending per student among local education agencies (LEAs) is generally affected by the size of the LEA, and more directly, by local board decisions.” In other words, really small LEAs (districts with less than 4K students or charter schools) have higher admin costs, but when it comes to large school districts (those with more than 4K students) the spending is influenced much more by local school boards, not the numbers of students.
Smaller Schools and Districts 