I therefore feel qualified to comment on the little flaw in this scheme: challenging schools don’t actually want bright, academically able teachers who want to make a difference.
Now, there might be a few well run schools that count as challenging, but schools that are well run soon improve. Any school that has been “challenging” for a considerable length of time will be run, or have been run, by idiots, those too stupid to either improve the school or to leave. The last thing they want is anyone with even half a brain asking questions or pointing out when something they are told makes no sense. There is an anti-academic, anti-intellectual, anti-thinking culture in these schools.