Ofsted is urging a new judgement-free approach for schools which have been stuck for many years on poor ratings.
It said the 410 "stuck" schools in isolated areas of England needed extra support, not to be inundated with unsuccessful improvement schemes.
Chief inspector of schools Amanda Spielman said a new non-judgemental approach was needed, offering the schools tailored support.
Heads said being stigmatised by blunt judgements made their jobs harder.
Marking quite a shift in its approach, Ofsted wants to offer such schools targeted assistance following more thorough and detailed inspections that are not tied to any judgement.
It is the kind of approach that head teachers have called for for decades, with the impact on schools of negative Ofsted judgements a big part of educational folklore.
Ofsted says so-called stuck schools, that is those that have not been labelled good since 2006, are grappling with numerous challenges.
'Carousel of consultants'
"We need to increase the depth of diagnoses we give these schools.
"We are recommending that the government funds Ofsted to trial a longer, deeper inspection approach with some of these schools, with the aim of not passing judgement but of enabling support to improve.
"We have made good progress with the Department for Education," it added.
Ms Spielman added: "What the remaining stuck schools need is tailored, specific and pragmatic advice that suits their circumstances - not a carousel of consultants. They are asking Ofsted to do more to help and we agree."
A spokesman for the Department for Education said it was working with Ofsted to look at how best to support these schools.
"We have also created a specialist academy trust to work with these schools and make improvements," it added.
School league tables
Deputy general secretary of the National Association of Head Teachers Nick Brook said stigmatising schools was not an effective way to improve them.
Stephen Rollet, of the Association of School and College Leaders, said the idea of a "non-judgemental approach" was helpful, but added the unintended consequences of school performance tables needed to be addressed.
"Instead of stigmatising these schools we need to make them places where teachers and leaders want to work."
An Ofsted report, In Fight or Flight? How stuck schools are overcoming isolation, says 415 schools serving 210,000 pupils have potentially left the equivalent of two whole school cohorts of children without a good education.
Such schools are often struggling with a combination of difficult issues which make it hard for them to get out of a rut.
These include issues like disengaged parents, so children are not encouraged to learn or even attend school, difficulties recruiting good teachers, often due to being overshadowed by larger towns nearby.
In recent years, such schools have been threatened with closure or conversion to an academy.
Ofsted said: "Some schools had a deep embedded school culture, resistant to change, with staff not believing that it was possible to overcome the factors that stood in the way of children receiving a good education.
"Other schools were chaotic and continually changing. For example, one school had been under the leadership of 14 different head teachers in 10 years."
It also highlighted how many of these schools had been "inundated with improvement initiatives from central and local government over the years, few of which have proved successful".