I am the 1997-1998 president of the Council of Professors of Instructional Supervision which includes members such as Thomas Sergiovanni, Ben Harris, Robert Anderson, Carl Glickman, Ed Pajak, Jerry Firth, Jeffery Glanz and others. I, too, have been arguing for this for a long time. The core of my argument is that a school district is a system. It is not sufficient to improve a single school within a district. Organizational improvement does not happen one school or one person at a time.
Many school districts have more than one high school.
I live in Howard County, Maryland. We have 8 high schools. Each high school has middle schools feeding into it. Each middle school has elementary schools feeding into it. On a piece of large flip chart paper write down the names of the high schools and all the middle and elementary schools that feed into them.