A two member group runs 70.000 computers at 200 schools in province Extremadura of Spain.
In the beginning 10 people was working full time setting up the system. Two persons works on the day to day operation today. Also they got a local caretaker at secondary schools just fixing simple hardware oriented issues which happens sometime with computers (keyboard failure, mouse which breaks, screens, replacing a broken computer).
In the city of Narvik they run 1500 computers with less than a man-year on 15 schools. Due to a question from a teacher to the mayor about changing to Windows, they did a calculation of cost removing Skolelinux in favor of Windows. The cost was 1,2 million Euro only for more expensive Windows hardware and Microsoft licenses with their school discount.
The city of Narvik didn't calculate the added cost of operating Windows over Skolelinux. But other municipalities running Windows in a school network,with 1500 computers are using 3-4 man-years on the operation.
We suspect it's a job security scam by Windows maintainers when fabricating that Linux in schools are more expensive, hiding the fact that their Microsoft dependent jobs get obsolete if they switch to Linux.
That and other schemes to prevent progress you should expect as the default from computer Luddites. Persons who are desperately trying to stop progress where most people now have switched to something else than Windows on their daily computer usage: