Manufacturers often put off
quality inspections until products go through the whole assembly line; when something goes wrong, they're left with the problem of figuring out where on the line the error occurred.
You can change the way schools are inspected as many times as you like (and Ofsted does — on average two substantial changes a year to
inspections frameworks or guidance since Michael Wilshaw became chief inspector in January 2012) but
until you can guarantee the
quality of the process (let alone the contentious debate about whether the right aspects of education are being looked at in a methodologically sound way), Ofsted
inspections will be flawed.